Replace included CoffeeScript library with the coffee-script gem

[netzpirat]

Haml Coffee Assets contains its own version of CoffeeScript. Replace that with the coffee-script gem. See also #37

[paulyoung]

Happy to look into this if you can explain some more about it.

[netzpirat]

Great. I'm talking about the Compiler, which uses ExecJS to create a JS runtime with the concatenated sources of CoffeeScript, Haml-Coffee and the Haml Coffee Assets compiler interface. Initially I tried to use the Ruby CoffeeScript compiler, but at that time I wasn't able to get it running in that way. Ideally we can use the Ruby CoffeeScript compiler that depends on coffee-script-source, so we don't need include our own version of CoffeeScript.