Block binding for loop single statement

This is my first (sort of) non-trivial pull request, so please bear with
me here. The important parts:

`code diff:` usrbincc@7c28d3df55df
`test diff:` usrbincc@4c2e6533a8f4

Everything else is reformatting and updating 'bin/traceur.js'.

I wasn't really sure where to put the TEST= and BUG=; so I put it in the
last commit. I'm not sure how well this convention transfers to github.

This fixes #231