Fixes https://github.com/feedjira/feedjira/issues/212

When the Atom parser is deciding which of the ```<link>``` elements present holds the URL for the feed, look for a ```<link>``` with rel="self". When deciding which is the website URL, if no ```<link>``` has type="text/html", return the href value for the last ```<link>``` in the XML which is not the feed ```<link>```, if possible.