Basic key, value selection by drag and drop
implement pivot function
Ability to change aggregation function per value
Multiple same value with different aggregations.
Add avg aggregation.
Take care of piechart
Beautifulize graph option
Fix value data reading
Remove some jshint warnings
Merge branch 'master' into pivot

Conflicts:
	zeppelin-web/app/scripts/controllers/notebook.js
Merge pull request #159 from NFLabs/pivot

Pivot