Revert "Revert "Merge pull request #151 from plone/syndication_improvements""

This reverts commit e7864ddcfa6794942f5f9810f91ba90872a4858c.
Revert "Test NewsML view and test render body option."

This reverts commit 8a520cea317f714151a7348f9fe9c2f3d4e8836b.
Revert "Move newsml_allowed and newsml_enabled from util to the view."

This reverts commit 658f8f32974dc32db8513236ec35c0f273e379fc.
Revert "Clean up newsml code, remove adapter and settings, manage everything in the view."

This reverts commit bd3c54094dbf2a817d1443627d8aa19475a3c664.
Revert "Implement NewsML feeds, ported from collective.syndication."

This reverts commit fc5cdcc62b431ee4714c30107ff53470ef8a8cc4.