Refactor UbloxGPSSensorController

- The module now interfaces SeonsorController, GPSSensorController and
AltimeterController have been deleted.
- The module now returns data corresponding to the keys passed to it as
  arguments.
Refactor UbloxGPSSensor

- Now UbloxGPSSensor is renamed to GPSSensor as it represents any GPS
  sensor, it now takes supported NMEA sentence types as args.
- UbloxGPSSensorController renamed to GPSSensorController as it
  represents a controller for any GPS module.
Refactor NMEASentenceParser

- The main change is that parse(String nmeaSentence) now returns a
  HashMap<String,String> instead of HashMap<String,Object>
Add tests for NMEASentenceParser