gui: Display miner ip:port on account page.

The miner ip:port are already present in the connected client info so
they can be displayed on the account page with only a minor change.

Previously only the name of the miner software and the hashrate were
displayed which made it impossible to distinguish which client was
which. Having the ip:port of the client isn't much better, but it's
definitely better than nothing.

internal/gui/assets/templates/account.html

@@ -79,13 +79,15 @@ <h1>Connected Clients</h1>
                     <thead>
                         <tr>
                             <th>Miner</th>
+                            <th>IP</th>
                             <th>Hash Rate</th>
                         </tr>
                     </thead>
                     <tbody id="account-clients-table">
                         {{ range .ConnectedClients }}
                         <tr>
                             <td>{{.Miner}}</td>
+                            <td>{{.IP}}</td>
                             <td>{{.HashRate}}</td>
                         </tr>
                         {{else}}