#8 Improved tests.

 - Added missing Task tests.

 - Added missing waveform retrieval client tests.

 - Removed unused PowerMockito dependency.

 - Import statics in tests.

 - Use Mockito annotations for mocks.

 - TODO: Still missing controller & gesture recognition tests.
Enabled lint checks in build.

 - Added min & target sdk

 - Allow backup

 - Fix ellipsis character