RSS feed converts relative urls to absolute urls

A common guideline is to use absolute urls instead of relative urls for RSS feeds. This is because some feed readers such as feedburner do not resolve the relative urls to the feed source domain. Relative urls also become a problem when people receive feed updates via email.

This pull request converts relative urls to absolute urls when compiling the RSS xml.

Please note that the request is against this commit: 
891870692d137792cabd6450bd972684cc6b5d07
Google Analytics now optionally supports setting _setDomainName using domain_name config value

I could not successfully get my current blog to work against the latest master of ruhoh.rb