Create onboarding modal [Fixes #76917104]

![screenshot 2014-08-28 19 05 56](https://cloud.githubusercontent.com/assets/1783869/4084343/e94943f4-2f07-11e4-8c46-5a05538f6e31.png)

ping @fatihacet 
If so, please don't it in stylus. The easy and much more efficient way is you can add the same class name to both of the modals. No need to create lots of duplicated css rules.