Added permissions:
[x] READ_PHONE_STATE so resend on network alive can work (see #29)
Bugfixes:
[x] Fix debug print in startForeground (#26)
[x] Back pressed was ignored
Enhancements:
[x] Treat anything but 'Activity.RESULT_OK' as SMS sent error (#27)
- Responses: Retry sending SMS automatically (#29) -> waits for network and resends the sms
- Requests: Show AlertDialog, ask the user if resend
[x] Support for multiple location requests arriving during a single GPS fix