General BT Framework updates for iOS & Arduino BT only app

- UI improvements (welcome message shows now, new label showing
connect/disconnect status, rssi message has dB string, light/sound
buttons disable when connection ends)
- App tries to connect to available BT devices matching service list
automatically and correctly (waits to receive right state from CB
central)
- Code cleanup in iOS
- A welcome message is now sent by T/LT to the phone upon connecting
- Created command enum structure for app to T/LT communication. This
will be the command protocol.
- PINs are reset now when phone connects to T/LT initially to clear out
initial stale states.
- Arduino loop() now has a BT message command handler