Gajim is not able to parse all allowed XEP-202 UTC date formats
Bug description
Gajim is unable to parse all allowed date formats found in the <utc> element of xep202 time stanzas. For example
\<iq id='uKc7l-44' type='result' to='flo@geekplace.eu/Gajim_' from='xxx'>
\<time xmlns='urn:xmpp:time'>
\<utc>2014-08-28T21:50:12.123+00:00\</utc>
\<tzo>+1:00\</tzo>
\</time>
\</iq>
is not parsed, ie. there is no value shown for "Contact time:".
XEP-202 2. says about 'utc': "The format MUST conform to the dateTime profile specified in XEP-0082 and MUST be expressed in UTC.". XEP-82 3.2 defines it as
CCYY-MM-DDThh:mm:ss[.sss]TZD
where TZD "MUST be either UTC (denoted by addition of the character 'Z' to the end of the string) or some offset from UTC (denoted by addition of '[+|-]' and 'hh:mm' to the end of the string)."
Looking at connection_handlers_events.py TimeResultReceivedEvent, gajim takes into account that the milliseconds are optional, but always assumes that the TZD is 'Z'.