Error information before running tests on Node 0.11.7

There is an error running tests under Node 0.11.7. It seems it's due to bug in Node/V8 https://github.com/joyent/node/issues/6235. Added version checking.

```
bartek@yoda:~/regenerator$ node -v
v0.11.7
bartek@yoda:~/regenerator$ npm test

> regenerator@0.1.6 test /home/bartek/regenerator
> node test/run.js



  wrapGenerator
    ✓ should be defined globally 
    ✓ should be a function 

  simple argument yielder
    ✓ should yield only its first argument 

  range generator
    ✓ should yield the empty range 
    ✓ should yield the range 0..n-1 

  collatz generator
    ✓ seven 
    ✓ fifty two 
    ✓ eighty two 

  try-catch generator
    ✓ should catch static exceptions properly 
    ✓ should catch dynamic exceptions properly 

  try-finally generator
    ✓ should execute finally blocks statically 
    ✓ should execute finally blocks dynamically 

  try-catch-finally generator
    ✓ should statically catch and then finalize 
    ✓ should dynamically catch and then finalize 

  dynamic exception
    ✓ should be dispatched correctly 

  nested finally blocks
    ✓ should statically execute in order 
    ✓ should dynamically execute in order 

  for-in loop generator
    ✓ should visit properties until 'skip' 

  yield chain
    ✓ should have correct associativity 

  object literal generator
    ✓ should yield the correct object 

  switch statement generator
    ✓ should jump to the correct cases 

  infinite sequence generator
    ✓ should generate a lot of plausible values 
    ✓ should allow limiting 

  generator function expression
    ✓ should behave just like a declared generator 

  generator reentry attempt
    ✓ should complain with a TypeError 

  completed generator
    ✓ should refuse to resume 

  delegated yield
    ✓ should delegate correctly 
    ✓ should cope with empty delegatees 
    ✓ should support deeper nesting 
    ✓ should pass sent values through 

  function declaration hoisting
    ✓ should work even if the declarations are out of order 

  the arguments object
    ✓ should work in simple variadic functions 
    ✓ should alias function parameters 
    ✓ should be shadowable by explicit declarations 
    ✓ should not get confused by properties 
    ✓ supports .callee 

  catch parameter shadowing
    ✓ should leave outer variables unmodified 
    ✓ should not replace variables defined in inner scopes 

  empty while loops
    ✓ should be preserved in generated code 


  39 passing (43ms)



  wrapGenerator
    ✓ should be defined globally 
    ✓ should be a function 

  simple argument yielder
    ✓ should yield only its first argument 

  range generator
    ✓ should yield the empty range 
    ✓ should yield the range 0..n-1 

  collatz generator
    ✓ seven 
    ✓ fifty two 
    ✓ eighty two 

  try-catch generator
    ✓ should catch static exceptions properly 
    ✓ should catch dynamic exceptions properly 

  try-finally generator
    ✓ should execute finally blocks statically 
    ✓ should execute finally blocks dynamically 

  try-catch-finally generator
    ✓ should statically catch and then finalize 
    ✓ should dynamically catch and then finalize 

  dynamic exception
    ✓ should be dispatched correctly 

  nested finally blocks
    ✓ should statically execute in order 
    ✓ should dynamically execute in order 

  for-in loop generator
    ✓ should visit properties until 'skip' 

  yield chain
    ✓ should have correct associativity 

  object literal generator
    ✓ should yield the correct object 

  switch statement generator
    ✓ should jump to the correct cases 

  infinite sequence generator
    ✓ should generate a lot of plausible values 
    ✓ should allow limiting 

  generator function expression
    ✓ should behave just like a declared generator 

  generator reentry attempt
    ✓ should complain with a TypeError 

  completed generator
    ✓ should refuse to resume 

  delegated yield
    ✓ should delegate correctly 
    ✓ should cope with empty delegatees 
    ✓ should support deeper nesting 
    ✓ should pass sent values through 

  function declaration hoisting
    ✓ should work even if the declarations are out of order 

  the arguments object
    ✓ should work in simple variadic functions 
    ✓ should alias function parameters 
    ✓ should be shadowable by explicit declarations 
    ✓ should not get confused by properties 
    ✓ supports .callee 

  catch parameter shadowing
    ✓ should leave outer variables unmodified 
    ✓ should not replace variables defined in inner scopes 

  empty while loops
    ✓ should be preserved in generated code 


  39 passing (58ms)


/home/bartek/regenerator/node_modules/browserify/node_modules/umd/node_modules/uglify-js/lib/parse.js:53
KEYWORDS = makePredicate(KEYWORDS);
         ^
util.debug: Use console.error instead
DEBUG: ERROR in file: /home/bartek/regenerator/node_modules/browserify/node_modules/umd/node_modules/uglify-js/lib/parse.js / ReferenceError: KEYWORDS is not defined
npm ERR! weird error 1
npm ERR! not ok code 0
bartek@yoda:~/regenerator$ nvm use 0.11.6
Now using node v0.11.6
bartek@yoda:~/regenerator$ npm test

> regenerator@0.1.6 test /home/bartek/regenerator
> node test/run.js



  wrapGenerator
    ✓ should be defined globally 
    ✓ should be a function 

  simple argument yielder
    ✓ should yield only its first argument 

  range generator
    ✓ should yield the empty range 
    ✓ should yield the range 0..n-1 

  collatz generator
    ✓ seven 
    ✓ fifty two 
    ✓ eighty two 

  try-catch generator
    ✓ should catch static exceptions properly 
    ✓ should catch dynamic exceptions properly 

  try-finally generator
    ✓ should execute finally blocks statically 
    ✓ should execute finally blocks dynamically 

  try-catch-finally generator
    ✓ should statically catch and then finalize 
    ✓ should dynamically catch and then finalize 

  dynamic exception
    ✓ should be dispatched correctly 

  nested finally blocks
    ✓ should statically execute in order 
    ✓ should dynamically execute in order 

  for-in loop generator
    ✓ should visit properties until 'skip' 

  yield chain
    ✓ should have correct associativity 

  object literal generator
    ✓ should yield the correct object 

  switch statement generator
    ✓ should jump to the correct cases 

  infinite sequence generator
    ✓ should generate a lot of plausible values 
    ✓ should allow limiting 

  generator function expression
    ✓ should behave just like a declared generator 

  generator reentry attempt
    ✓ should complain with a TypeError 

  completed generator
    ✓ should refuse to resume 

  delegated yield
    ✓ should delegate correctly 
    ✓ should cope with empty delegatees 
    ✓ should support deeper nesting 
    ✓ should pass sent values through 

  function declaration hoisting
    ✓ should work even if the declarations are out of order 

  the arguments object
    ✓ should work in simple variadic functions 
    ✓ should alias function parameters 
    ✓ should be shadowable by explicit declarations 
    ✓ should not get confused by properties 
    ✓ supports .callee 

  catch parameter shadowing
    ✓ should leave outer variables unmodified 
    ✓ should not replace variables defined in inner scopes 

  empty while loops
    ✓ should be preserved in generated code 


  39 passing (44ms)



  wrapGenerator
    ✓ should be defined globally 
    ✓ should be a function 

  simple argument yielder
    ✓ should yield only its first argument 

  range generator
    ✓ should yield the empty range 
    ✓ should yield the range 0..n-1 

  collatz generator
    ✓ seven 
    ✓ fifty two 
    ✓ eighty two 

  try-catch generator
    ✓ should catch static exceptions properly 
    ✓ should catch dynamic exceptions properly 

  try-finally generator
    ✓ should execute finally blocks statically 
    ✓ should execute finally blocks dynamically 

  try-catch-finally generator
    ✓ should statically catch and then finalize 
    ✓ should dynamically catch and then finalize 

  dynamic exception
    ✓ should be dispatched correctly 

  nested finally blocks
    ✓ should statically execute in order 
    ✓ should dynamically execute in order 

  for-in loop generator
    ✓ should visit properties until 'skip' 

  yield chain
    ✓ should have correct associativity 

  object literal generator
    ✓ should yield the correct object 

  switch statement generator
    ✓ should jump to the correct cases 

  infinite sequence generator
    ✓ should generate a lot of plausible values 
    ✓ should allow limiting 

  generator function expression
    ✓ should behave just like a declared generator 

  generator reentry attempt
    ✓ should complain with a TypeError 

  completed generator
    ✓ should refuse to resume 

  delegated yield
    ✓ should delegate correctly 
    ✓ should cope with empty delegatees 
    ✓ should support deeper nesting 
    ✓ should pass sent values through 

  function declaration hoisting
    ✓ should work even if the declarations are out of order 

  the arguments object
    ✓ should work in simple variadic functions 
    ✓ should alias function parameters 
    ✓ should be shadowable by explicit declarations 
    ✓ should not get confused by properties 
    ✓ supports .callee 

  catch parameter shadowing
    ✓ should leave outer variables unmodified 
    ✓ should not replace variables defined in inner scopes 

  empty while loops
    ✓ should be preserved in generated code 


  39 passing (54ms)
```