Fix regression in _coffee binary handler for scripts with no extension.

See: https://github.com/aseemk/streamlinejs/commit/f0b5a06ce530a3f17aa5c6ceae212b4e6145f194#commitcomment-5339141
Merge pull request #205 from aseemk/coffeescript-1.7-support

Fix regression after CoffeeScript 1.7 support