amberc: remove now duplicate flag for closure compiler
amberc: remove flag for optimizing single files
amberc: remove code for calling Google Closure compiler
amberc: remove commandline options for calling closure compiler
grunt-amberc: remove code for dealing with closure compiler
grunt-amberc: update inline documentation
Merge pull request #683 from mkroehnert/grunt-closure

Remove Google Closure compiler support from the amberc compiler