Use sqlite database for state

[jwoglom]

ControlX2 is currently a stateless application, ignoring the fields it saves for settings.

This story tracks wiring up a SQLite database and associated schemas to the app so that it can store its own information about the pump's state, which can then be used by other subcomponents (like the history log fetcher or nightscout uploader).

Until sqlite is configured to store state, we can't implement many necessary features.

[jwoglom]

Work-in-progress implementation using the android room library on the dev branch.