charts for dashboard

  [PT 49574083] interview chart
  [PT 49574095] offer chart
[BUG 49897123] fix crash issue
[PT 49574095] change offer chart data source
Merge pull request #153 from Chunjie/master

charts for dashboard
Merge remote-tracking branch 'vmw-tmpst/master' into action_items

Conflicts:
	app/models/interview.rb