[scripts-announce] MediaWiki upgraded to v1.5.8

[presbrey@MIT.EDU]

We have upgraded all MediaWiki installations to v1.5.8 in response to 
security vulnerabilities announced by the MediaWiki developers.

You did not receive this update if you opted out of security updates or if 
you installed MediaWiki without using the automatic Athena installer.

If you notice any problems with your upgraded wiki, please let us know by 
emailing scripts at mit.edu.

--Joe