Moved all the tabs related stuff into SwipeableTabsFragment.

Move stuff related to creating the tabs and the PageViewer into a
separate class, which can then be reused by multiple sections.
Added new fragments for tabs and adjusted hierarchy.

- Split the classes to make them much more modular
- Add tabs for Mobile and Bluetooth (the content is still dummy as of
  now)
- Added new package namespaces to get better hierarchy.