Time zone widget

Hi Philipp, all,

I added a small template that links to a website that will translate the
time of the meeting into local timezones. You can see it in use on the front
page<http://www.w3.org/community/ontolex/wiki/Main_Page#Future_teleconferences>of
the Wiki.

It is used as follows:

{{time|hour=12|minute=00|year=2013|month=04|day=26}}

Where the time is given in UTC (2 hours behind European Summer Time)

Hopefully, this should help people to find the correct time for the meeting

Regards,
John