Add yield to keywords

Because new coffeescript versions supports generators.
Merge pull request #194 from yetanotherusernamebecausegithubisbugged/patch-1

Add yield to keywords
Merge remote-tracking branch 'upstream/master'

Conflicts:
	CoffeeScript.tmLanguage
Merge branch 'master' of github.com:icflorescu/sublime-better-coffeescript