MH-9131 Updated Atom 1.0 feed to be valid. Tried to do only minor changes to the data in RSS feeds. Did not check Atom 0.3 feeds as they are depricated. Added more optional data to the Atom feed that might be useful for adopters. Linked in the UI to the Atom 1.0 feed now.

git-svn-id: https://opencast.jira.com/svn/MH/trunk@13936 e6edf6fb-f266-4316-afb4-e53d95876a76