Change the name of the gateway to its location.

This way, the notification shows the city of the gateway rather than the
hostname :)
Extracted methods from some chunks of code.

This is a first step for a refactoring of the EIP class.
Removed retrieveVpnService, it seems unuseful.

I've tested autostart, on+off repeated times, and switch provider. It
works.

The ServiceConnection is managed by DisconnectVPN from ics-openvpn, it's
not useful.
Udp as default transport + minor refactoring.

I've also added a check for a nullpointer when eipDefinition is
null.
Refactor setting gateway name
Merge branch 'feature/Show-location-in-openvpn-notification-message-#4665' into develop