Adds commits calendar with ajax request to user profiles

Calendar of commits in user profiles

When user has commits, it will show a calendar covering a timeframe from the year before up to his latest commit
![fdf6190a-e577-11e3-8af6-afc3f15771d8](https://cloud.githubusercontent.com/assets/6151901/3113403/06598df6-e6d7-11e3-820c-2d66ce6bad58.gif)

When user has no commits, it will show a timeframe up to the current month
![fe7f355a-e577-11e3-9ded-ff902e828c24](https://cloud.githubusercontent.com/assets/6151901/3113408/1eeb686c-e6d7-11e3-9079-f63723b2d7cd.gif)

@randx this is from #6958 we, @kbleabres and I, added ajax request and edited some lines