Battery saving and new map tiles

- Implements the suggested battery saving from issue https://github.com/SecUpwN/Android-IMSI-Catcher-Detector/issues/87 - needs a lot of testing though as it's hard to test everything and make sure it's working as expected. Logcat output will show enabling/disabling of GPS requests.
- Implements multiple map tiles for the Map view, e.g. satellite and terrain