Update to JUnit 4 Tests

See : https://docs.google.com/presentation/d/1EtFKPluGiuxZcr4W_cAziEY_--wbY_1otw44XEBv7JA/edit

In General we need to

• Update to JUnit 4
• Remove references to ActivityInstrumentationTestCase2
• Use the newer injected mocks where appropriate