Test262 integration

Initial changes to be able to run the test262 suite from our code.

Things to pay attention to:

1. We are not using submodules, nor similar - we expect the test626/ repo to be cloned and be sitting next to echo-js/.
2. Created a small coffee script, test/ejs-test-wrapper, to compile + run a given .js file - we *need* to pass a command file to test262.
3. Create a small bash file to run the test (maybe we could include it in our Makefile?). So far it can take an optional parameter, to run only a specific section of the schema, i.e. (inside echo-js/):

 test/run-test262.sh es6

Will only run the tests that are part of the es6 section (other ones could be 'ch06', 'ch07', etc). If none given, it will run everything.

Current issues:

1. eval() - need a patch for test262/
2. we pass the --warn-on-undeclared flag, so we don't fail in code checking for node (and which never hits us nor SpiderMonkey, in theory).
3. There's a test case in the chapter 12 that hangs a complete run - I'm taking a look at which one it is.

Thoughts?