Adds content and styles the new page geststarted

Hi!

This is related to https://github.com/owncloud/owncloud.org/pull/369.

 I made the popups work.

This is how it looks now, it is possible two variations, with or without buttons:

![page-getstarted_buttons](https://cloud.githubusercontent.com/assets/241266/5415147/36f15b94-8225-11e4-9443-8294fc3b90d5.png)

![page-getstarted_links](https://cloud.githubusercontent.com/assets/241266/5415153/3e3735cc-8225-11e4-8dd8-6a7afe68a9c5.png)