Get rid of instrumentation tests

[passsy]

The android instrumentation tests are slow, and starting the emulator takes ages. (reference #116) Also the environment is flaky. Builds continue to fail because the emulator startup fails or the apk cannot be installed.

We only have a few instrumentation tests. Maybe we can convert them to unit tests (with some effort). Also we can get rid of the CompositeAndroid instrumentation tests once we get rid of this module #109.