Tighten formatting of Facebook Rss Title

The stock PCL compliant WebUtility.HtmlDecode behaves differently on
Windows Phone and Windows 8.  Most notably, it did not correctly decode
the "@" character on Windows Phone.  More details can be found @
http://stackoverflow.com/questions/17352981/webutility-htmldecode-vs-httputilty-htmldecode

To overcome this difference HttpUtility.HtmlDecode was implemented in a
PCL compliant way.