Android 4.2.2 build

Lower the target android version to API 17 / 4.2.2.

Pre-release

1. Install UnifiedNlp (https://github.com/microg/android_packages_apps_UnifiedNlp) on /system/priv-app
2. Install GSMLocation-v0.0.1.2.apk (adb install, /data/app is ok)
3. Open the "NLP Controller" and select it as a backend :-)

The backend will need some time to initialize. This is due to the fact that it extracts a 135MB opencellid binary dump. Be patient, it will initialize at some point. I also found it usefull to reboot the device after adding the provider.