JIRA XWIKI-479 Redirect loop if xwiki.virtual.redirect is not specified, and it is commented out and has unhelpful value by default.

fyi: I've entered the following bug:* *Affects Version/s: 0.9.1252 If xwiki.virtual.redirect is not specified for a virtual wiki, attempting to access a subdomain that does not correspond to a wiki causes the browser to be redirected repeatedly to the same invalid url. xwiki.virtual.redirect is commented out and has an unhelpful value by default. (The default is ...127.0.0.1/..., but a valid external URL is needed.) -Trevor