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'
Switched to grunt-contrib-compress, added tar.gz archive
Adjusted margins
Fix for #355
Make panel extra icons more obvious, fix overlap, add tooltips, add method for panels to define custom modals
improve panel extra icon hover
removed redundant divs
Added interval selector to histogram
Added interval options to panel