Upgrade Atom from 0.3 to 1.0

Atom 1.0 is almost out of the door so I prepared the atom.module to conform to 1.0 spec

Test feed: http://kika.trip.ee/atom.xml

It validates: http://feedvalidator.org/check.cgi?url=http%3A%2F%2Fkika.trip.ee%2Fatom.xml

See http://atompub.org/2005/07/11/draft-ietf-atompub-format-10.html