rollback to appcompat v20

v21 appears to just not be ready for production given the bugs.
// FREEBIE
Don't completely disable GCM.

// FREEBIE
Updated translations.

// FREEBIE
Bump version to 2.3.1

// FREEBIE
The future is the other direction.

// FREEBIE
Add callback method parameter to axolotl decrypt functions.

// FREEBIE
Guard against fragment disappearing before callback.

// FREEBIE
Do thread trimming as JobManager job rather than AsyncTask.

// FREEBIE
reorder window feature requests in MediaPreviewActivity

ActionBar is initialized in a different way by AppCompat v20 compared to
ABS or v21 even...
// FREEBIE
fix for ringtone selection with android-support-v4-preferencefragment
Try to fix LGE menu button NPEs
fix based on https://code.google.com/p/android/issues/detail?id=78154

// FREEBIE
Revert "Try to fix LGE menu button NPEs"

This reverts commit f3a3aaca6051b5ae464c026ff8d72e51a1d5a8a6.
compat actionbar bg for dark theme

// FREEBIE
Bump version to 2.3.2

// FREEBIE
PushNetworkException for network errors on external downloads.

Closes #2112
Fixes #1264

// FREEBIE
Minor cleanup.

// FREEBIE
Move directory refresh from a service over to a job.

// FREEBIE
Move JobManager to external project and dependency.

// FREEBIE
Display 'me' for device's local number in group membership list.

// FREEBIE

Fixes #1494
Closes #1505
replace numbers with names and make strings translatable