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 
But the modals will be shown at the same time, right? If so it shouldn't. This is because 2 overlays will be shown at the background and will make IDE darker and also it's not ideal.