add git-it workshop

Hello, yes, I made a workshop!

It's called Git-it and it's on Git and :octocat: basics. I've added it as an orange box on the page:

![screen shot 2014-01-27 at 7 08 37 pm](https://f.cloud.github.com/assets/1305617/2015963/993ad9a8-87c9-11e3-8f8e-4ed707001457.png)

:octopus: :cat2: