Add support for telling end user when masternodes start successfully

[mcmickburns]

Send OK message like the daemon does when the masternode starts successfully in phantom?
Example: https://github.com/EmpireCryptoNetwork/emp/blob/22d89c5968e3df795b37d34e2d4416936aac03b3/src/activemasternode.cpp#L493

CActiveMasternode::EnableHotColdMasterNode() - Enabled! You may shut down the cold daemon.

So the end user knows its actually enabled?

Phantom could check that it was working by requesting an update on itself with DSEG.
it'd basically ask another peer for information on itself, then check that the last seen time matched.

Phantoms could verify themselves as working from their peers.

DSEG is a beefy damn call though, only concern I've really got. it'll get you banned too unless you're very very careful on the time windows
wait DSEG with a specific MN is unlimited I believe, it's only a global DSEG

You can send out a DSEG + MN_OUTPOINT -> get back info.
The only thing I'm not sure about is if the MNB it's going to send is updated, I'm guessing it is

            uint256 hash = mnb.GetHash();
            if (mnodeman.mapSeenMasternodeBroadcast.count(hash)) {
                mnodeman.mapSeenMasternodeBroadcast[hash].lastPing = *this;
            }