Remove some libs in favor of Maven dependencies (including updates for DiskLruCache and Gson)
Remove CWAC lib in favor of custom implementation; refactor service scheduling
Remove deprecated GCM lib and use GMS instead
Update image cache keys to match new DiskLruCache restrictions
Use constants for preference names
Proper name for wakelock
Fix doc
Use constants for intent extras
Use constants for previously missed prefs
Fix some more docs
Simplify string resource access
Fix intent extras access