Download certificate if expired.
Fetch new certificate and restart EIP.
If authentication fails, restart eip.

This happens when we update the openvpn certificate, in the first
connection attempt.
New certificate if half of its lifetime passed.

It takes for granted that the certificate is valid from the very same
date it's downloaded.
Merge branch 'bug/Certificate-expiration-#5821' into develop
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