Process Android Lint warnings.

Lint reported two NewApi violations, but both are properly guarded.
[android] On-device tests with Espresso.

I wanted to check out Espresso: http://code.google.com/p/android-test-kit/

This commit adds an instrumentation test to the "stubbed" product flavor that
clicks every main menu item in turn and checks for evidence that it worked as
expected. It disables ProGuard optimization for DEBUG builds because the new
jar file gave warnings that I didn't care to investigate or surpress.

To run the test suite, execute `gradle connectedInstrumentTestStubbedDebug`.

Espresso or no, Android Instrumentation is still painful. Had to @FlakyTest
every single case.  The four that target the sliding screen could probably have
been saved by disabling animations at the OS level. I'm not exactly looking
forward to going into and out of the development menu twenty odd times per day,
so I went with @FlakyTest and Thread.sleep() instead. The sad truth is an app
needs to be a lot bigger than this one before Instrumentation starts giving a
positive RoF (Return on Frustration).

Robolectric FTW.