Enhanced logic to start/stop gogoc upon network status change

* Do not stop gogoc in case of failover
* Only start gogoc if auto_connect is set or gogoc was previously
  connected/connecting
* Removed checkNetworkConnection method
* auto_connect setting default value is false
Set preferences file name to "preferences"
Add a little code comment
Enhance gogoc start/stop logic

* Set lastStatus in statusConnection method
* Properly fetch shared preferences
* stop gogoc if there is no network available or: if there is no
  connection attempt nor failover state.