Mark configuration strings as non-translatable.

10 out of 36 strings in config.xml were not marked as non-translatable,
making pseudolocalization handle them incorrectly and leading to
potential issues with unexpected translations. Added translatable="false"
to all of them for consistency.

Change-Id: I55d8b0c24834722e71fa3e89ae508a95839416e9
Out of memory using wallpaperPicker switching wallpapers

Out of memory issues arise when switching wallpapers using
WallpaperPicker quickly, due to not releasing large Bitmaps
before allocating space for new ones.

Resolved by securing that wallpaper bitmaps are set to null
in order to be garbage collected when switching wallpaper.

Added stability correction making sure noone can retrieve
bitmap once it has been recycled by first calling
WallpaperManager.forgetLoadedWallpaper().

Change-Id: I318ee46d8613bec15dd52dd7b61ae950e760e6f6
Avoid duplicate call to onLoadFinished()

When a loader is initialized in Fragment#onActivityCreated(Bundle), then
LoadersCallback#onLoadFinished() was called twice on device orientation
change:
 - once during fragment start();
 - once during loader finishRetain().

Reported as bug 63179:
https://code.google.com/p/android/issues/detail?id=63179

This commit prevents to call onLoadFinished() when the data has already
been delivered.

Change-Id: I893013049f819dd5543a8079ce9d8025a5fdb2f1