ENH: UTC Date String pattern added to datedetector

I added this date pattern to facilitate Fail2Ban date recognition for the date formats outputted in Node.js Express/Connect server logs. The Connect source currently formats a Javascript date using toUTCString() and logs that, creating logs resembling the following line:

127.0.0.1 - - [Wed, 31 Jul 2013 16:24:11 GMT] "GET / HTTP/1.1" 404

Previously running an anchored ^ failregex on this log format resulted in the following message: "Please contact the author in order to get support for this format". Hopefully this will make Fail2ban easier to deploy for Node.js environments.