Add Unit/Instrumentation tests

The app currently has almost no tests. This was due to the high involvement of android's native components related to Custom View and Bitmap. Since the foundational part is now been implemented, it's a good time to escalate the code coverage by adding the instrumentation as well as robolectric based Unit tests.

No files, tests, or entry points are named. Start by mapping the existing Custom View and Bitmap code and checking the current test setup; done means adding both instrumentation tests and Robolectric-based unit tests for the foundational behavior.

Written by the indexing model from the issue text.