Fixed notifications too (forgot to do it in another branch, it's #5964).

When the user has already been connected to a VPN and she configured the
client to use persistent-tun, we should warn her that until the VPN
connection is again established, no traffic will flow.

It's enough to reflect the fact that the button leads to a dialog from
which the user can both log in or sign up.

I don't use the eip status receiver because it wasn't reliable on
timing: updated messages were arriving before the receiver was notifying
a new state.

Current and last ConnectionStatus is now managed at EIP.

More refactoring on the eip fragment, now there are separate methods for
setting up the UI depending on the message received.