Basic coffeescript highlighting

From https://github.com/dnagir/highlightjs-coffeescript

Closes #2

README.md

@@ -166,3 +166,4 @@ SOFTWARE
 
 * jQuery: MIT/GPL license
 * highlight.js: Copyright © 2006, Ivan Sagalaev
+* highlightjs-coffeescript: WTFPL - Copyright © 2011, Dmytrii Nagirniak

static/application.js

@@ -167,7 +167,7 @@ haste.extensionMap = {
   lua: 'lua', pas: 'delphi', java: 'java', cpp: 'cpp', cc: 'cpp', m: 'objectivec',
   vala: 'vala', cs: 'cs', sql: 'sql', sm: 'smalltalk', lisp: 'lisp', ini: 'ini',
   diff: 'diff', bash: 'bash', sh: 'bash', tex: 'tex', erl: 'erlang', hs: 'haskell',
-  md: 'markdown', txt: ''
+  md: 'markdown', txt: '', coffee: 'coffee'
 };
 
 // Look up the extension preferred for a type