Use Pollexor 2.0
Merge pull request #407 from square/dimitris/pollexor2

Use Pollexor 2.0
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
Merge branch 'master' into disk-cache

Conflicts:
	picasso/src/test/java/com/squareup/picasso/DispatcherTest.java