Big update and many bug fixes

Android app:
App now reads the sample rate and frequency sweep parameters on
connection so both devices are always in sync.

Robust poka yokes to prevent erroneous values to be entered for
frequency sweeps and sample rate.

Sample rates and frequency sweeps can now be set even if data is not
being collected.

Arduino:

Added time out state and boolean. If a time out occurs, LED will not
blink at all.

Firmware:

Updated firmware to allow modification of local server GATT database by
the server on start up. Used to initialize values read by app on start
up.

Miscellaneous bug fixes.