Layout tweaks, optimisations and font changes

Use Roboto thin font on API 16+ (Android 4.1) devices (Why not?)
Changed some LinearLayouts to RelativeLayout and removed some superflous layout
 nesting. I have tried to keep the original structure here and just refactor
 some layouts.
Fix some warnings about using the fontFamily attribute on pre-API 16 devices by
 including new values/styles.xml file.
Some font size changes - making some things slightly bigger and easy to read.

These layout and UI changes are open to review and may change.
 Hopefully by flattening some nested layouts there will be a performance
 improvement, although proper performance testing has not been done (and the
 impact is expected to be negligable in comparison to better data caching).

Change-Id: Ie6b8f063e9c941197e10684d1f4d79fa18efe28b
Merge "Layout tweaks, optimisations and font changes"