We should show the error in conv_textview when we cannot join room
DEBUG: socket got \<presence iperror='' type='error' to='jim@jid/GaJim' from='test/t@chat.jabberfr.org/Jim' id='270'>
\<x xmlns='vcard-temp:x:update'>
\<photo>e5e3fccc721e5fdd2bc01ba56e85c778bc4d364d\</photo>
\</x>
\<c node='http://gajim.org/caps' ext='ftrans' ver='0.10.1.5' xmlns='http://jabber.org/protocol/caps'/>
\<x xmlns='http://jabber.org/protocol/muc'/>
\<error type='wait' code='502'>
\<service-unavailable xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
\<text xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'>Unable to resolve hostname.\</text>
\</error>
\</presence>