Adds version page

This PR requires: https://github.com/libgdx/libgdx/pull/1893

This page displays the following:
* Latest LibGDX release version
* Latest LibGDX snapshot version
* Respective versions of all dependent plugins/projects

It does this by querying a .txt file that is built by the gdx-setup ant build, and by using the github API.

![Example](http://i.imgur.com/Nb2tLAJ.png)


Not sure where this is best suited, so I have left out placement on the menu bar or any links as of yet.