feat(runtime): add memoization to genericType()
Support glob patterns in file names while compiling with --out

Hi guys,

I would like for the compiler to support shell patterns in sources' file names when compiling with --out option. Currently we can either use module names or file names/full paths while listing sources for compilation. That is, for example, we are currently doing this:

`traceur --out compiled.js module1.es6.js module2.es6.js module3.es6.js`

with patterns we can do it like this:

`traceur --out compiled.js *.es6.js`

or use any other pattern that glob library supports.

This patch doesn't add much in terms of complexity and since the glob library is already used in the project, we also don't need any new dependencies. It shouldn't cause problems with backwards compatibility because it only affects file names that use glob's special symbols (*, ?, [, ], etc) which are not normally used in file/module names.

Review URL: https://api.github.com/repos/google/traceur-compiler/issues/1542

Closes #1542.
Don't call require('path') in the runtime unless --require is used.

Drive-by: remove redundant code in runtime.js.
Fixes #1531

Review URL: https://api.github.com/repos/google/traceur-compiler/issues/1543

Closes #1543, closes #1531.
Correct the key for sourcemaps in mode 'memory'
Add unit test for sourceMaps:memory from interpreter
Add sourceURL when the input name differs from output name.
respond to review
Debug output for Travis