UI overhaul, now much more responsive to screen size/width:

- Associated a color with each player. Added a color picker to the add player dialog.
- Switched to GridView to display player data. The number of columns scales based on device width.
- The container for player data has been redesigned to be more visually appealing.
- Implemented a custom selector for the player data container (pressed/activated states).
- Switched to Theme.Holo.Light.DarkActionBar.
- Improved visual appearance of bottom bar.
- Implemented custom selectors for bottom bar image buttons.
- Removed titles from dialog boxes to reduce screen space usage.