POC: Updated contrib calendar

In an effort to cut down the JS file size - i've removed the heatmap calendar used for the contributing calendar on users profiles. We already have d3 on the page so why not use it instead of using a library which uses it?

![Screen_Shot_2016-04-27_at_11.08.41](/uploads/64c40f0c766f800fd0e33ac8be7f9644/Screen_Shot_2016-04-27_at_11.08.41.png)

cc. @jschatz1 

See merge request !3944