fix(hub): Disconnect issue (MAX_CLIENTS=6)

- Add error handler to the XMPP 'login' client
- Reject promises in both error handlers
- Enable auto-reconnection

lib/#/hub.js

@@ -46,8 +46,9 @@ function getIdentity (hubhost, hubport) {
   })
 
   xmppClient.on('error', function (e) {
-    debug('XMPP client error')
-    console.log('errorhub', e)
+    debug('XMPP client error', e)
+    xmppClient.end()
+    deferred.reject(e)
   })
 
   xmppClient.on('stanza', function (stanza) {
@@ -101,6 +102,12 @@ function loginWithIdentity (identity, hubhost, hubport) {
     disallowTLS: true
   })
 
+  xmppClient.on('error', function (e) {
+    debug('XMPP login error', e)
+    xmppClient.end()
+    deferred.reject(e)
+  })
+
   xmppClient.once('online', function () {
     debug('XMPP client connected using identity token')
     deferred.resolve(xmppClient)