Add timezone information to notification email

The watchlist email sends out the time of any modification (and also the subject line of the email) using the local time of the server where the XWiki is running. We have an XWiki instance which is accessed by people in 8 different time zones, and the server running the instance is in a whole other timezone. It would be useful to add the timezone next to the time in the emails.

Further, it might be an option to add timezone as an attribute of the XWikiUsers class and maybe convert data to the local timezone of the user when sending out emails (with the timezone identification as requested above).