Show an activity when the user is disconnnected from the server.

This ensures that the user is not seeing stale content (e.g., a list
of albums) that they cannot interact with.
Merge remote-tracking branch 'kaaholst/actionbar' into actionbar

* kaaholst/actionbar:
  ActionBarCompat: Support action bar items setEnabled/setVisibility
  Fix crash on orientation change when volume panel is showing
  Fix item list problems with orientation change
  Fix header lost after orientation change
  Use spaces (instead of tabs) for indentation
  Do not use the Squeezer prefix for new files/classes
  Rename savePosition to saveVisiblePosition, and add javadoc
  Implement album grid layout
Show the NowPlayingFragment in the album grid view.

The GridView was consuming all available space, leaving none for the
NowPlayingFragment.  Set the GridView's height to 0dip with a weight of
1 to force it consume only spare space.
Simplify the per-item grid layout.

grid_item.xml:

- Use a RelativeLayout instead of a series of nested LinearLayouts.

- Remove the marquee effect from the TextViews, it dramatically slows down
  scrolling performance.

- Adjust padding for consistency.

item_grid.xml:

- Adjust padding for consistency.

- Add a weight to the ProgressBar, so that it also pushes NowPlayingFragment
  to the bottom of the screen, preventing an awkward transition if it takes
  a while to load content.

AlbumGridView.java:

- Remove marquee related code.
Merge remote-tracking branch 'nik/actionbar' into actionbar
Clear adapter and show load in progress when items are reordered

Restore functionality for the above, which was lost when implementing
retain item lists on orientation change.
Also fix registration of received pages.