Have servers advertise their Bitcoin Core or XT version

[TheButterZone]

From nerioseole at https://bitcointalk.org/index.php?topic=1109497.0

"Electrum-Servers have to operate a full Bitcoin-core node.

In the light of the recent events on the Bitcoin network, and the short fork on the network, it would be great if the Servers would advertise in their console (tab) msg (where they list their donation address) the Bitcoin-core version they are operating with! (or if they are using Bitcoin-XT...)"

[MuhammedZakir]

I second this.

[EagleTM]

It seems to work well on a voluntary basis in the server banner.
The verison info can actually be retrieved from bitcoin-core with a cli call:
https://www.reddit.com/r/Bitcoin/comments/3c305f/if_you_are_using_any_wallet_other_than_bitcoin/cstt2vb

Not sure what the client would do with the info exactly - possibly warn if it's too low. It could be faked but there is little point for the operator...

[TheButterZone]

How does an Electrum 2.3.2 user get any return from the server they're connected to, using console commands, other than "Traceback (most recent call last):" ?

getinfo
Traceback (most recent call last):
getnetworkinfo
Traceback (most recent call last):

[ahmedbodi]

I believe ive done this in: #139