Adding back stack percentage for histogram

Conflicts:
	panels/histogram/module.js
moved the aws config out of the general gruntfile setup, and into a task that is only run when needed.
Merge remote-tracking branch 'selvakn/master' into stackPercent
Cleaned up the Grunt config a bit, removed an unneeded dep
Merge pull request #514 from spenceralger/gruntfile-cleanup

Cleaned up the Grunt config a bit, removed an unneeded dep
Readded percent stacking, fixed bug when area = 0, added view options to histogram outside of editor
Merge branch 'stackPercent'