code style : wrap some lines that exceeds 120 characters, replace some '=>' by '->'

Server side modification.
Essentially line wrapping, but please review carefully, I'm coffeescript beginner.

Tests don't passed before modification and they don't pass after. This is my next mission, unit test.
$ ./bin/coco-server-test-runner 
Watching for changes in /home/smoratinos/git/codecombat/test/server/
........TypeError: Cannot read property 'description' of undefined
    at Request.func [as _callback] (/home/smoratinos/git/codecombat/test/server/file.spec.coffee:27:29)