Lint Issue Fix from #180
Properly center both label and number and simplify layout.
Improve file and comments icons.

Provide them in higher resolution and use the holo color scheme to match
the other drawables.
Improve file manager row layout.

Use non-deprecated size names, and properly center the icon.
Properly fix #174.

Re-use inflated header view instead of reinflating layout.
Don't prevent destroying fragments.

It might lead to multiple fragments being incorrectly attached; and we
prevent unneeded destroyings via getItemPosition() already.
Update to latest build tools.
Design Improvements #178

- Branch selection
- Margins and links
- Using attrs to set file explorer icons according to theme
- Make "View More" Button more visible and cleaner
Make sure to keep all fragments alive.

We only have a maximum of 4 pages anyway, so make sure they're not
needlessly destroyed once loaded, especially as they each do network
I/O.
Merge branch 'lint-issue-fix' of https://github.com/kageiit/gh4a
Merge branch 'for-upstream' of https://github.com/maniac103/gh4a
Merge branch 'for-upstream-ux' of https://github.com/maniac103/gh4a
Merge branch 'for-upstream-fixes' of https://github.com/maniac103/gh4a