support starting when network is not available
sometimes goimapnotify starts before the network is up on my laptop, and fails immediately:
FATA[0000] something went wrong creating IDLE client: dial tcp: lookup imap.example.com on [::1]:53: dial udp [::1]:53: socket: address family not supported by protocol
It would be nice if it just went into a continuous, delayed retry loop so that it'll eventually succeed once the network is up.