Assisted gps service

[andresR8]

configures the Assited Gps Service at init. First it makes a request to ublox agps services, and then save the config file on a preconfigured path onto the system. It also checks the if the file is still valid to avoid overload the ublox server. After, it sends a cold reset to the gps module, the actual time, and finally the .ubx config file obtained from the ublox server.