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/6151901/3112882/ec2df25c-e6ca-11e3-868f-6969ea3f7620.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/6151901/3112883/ec2e261e-e6ca-11e3-8e31-6de01a6ff0b8.gif)