Added a log to report registration removal

Bug: 8239532

Stopped updating context on every broadcast reception
Made some code reduction - sharing code in DigitalWidgetViewsFactory
Replaced intent literal strings with the constants

Fixed a deprecated reference
Added some commentary
Renamed some variables to improve clarity
Cleaned up the lint warnings

Change-Id: Icb38fcdec2104a271bc429b74430e7ff371d4098