Extra null check onReceive

- Fix NPE for `onReceive` with `null` extras
- Add some test for `onReceive` with `null` conditions
- Condition yoda remove
Deprecate G+ community in favor of StackOverflow.
Second pass based on feedback
- Refactor NetworkBroadcastReceiver for testing
- Refactor tests to actually test behaviour
- Introduce Util.getService cause long lines and everytime casting suck
Rename verifyAirplaneMode to setAndVerifyAirplaneMode
Merge pull request #411 from eveliotc/extra-null-check

Extra null check onReceive