- Refactor UI (use Material Design and new font, drop to single style.xml)
- Do the pump comms using an IntentService in a separate thread
- Add extra OTG check
- General clean up and refactoring (improve naming and code).

Code cleanup and minor refactoring to improve maintainability and the ability to internationalise the app.
Fixes #43

Removed a whole bunch of code we don't use. Everything is still working. Quick! Commit, before you break something!

Fix #12

Fix #6

Remove hardcoded keys.