[#33838] Generate version of atom feed from JVersion

http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=33838&start=0

## Testing Instructions
Check an atom feed of a component. Before patch the < generator > tag will show the version as 1.6. After patch it will show 3.3 (and pulls the version number from JVersion so will not need updating in the future)
If we do something that isn't semver then literally all sites are screwed anyhow that expect that for version_compare() statements so i think there would be bigger problems/uproars. Anyhow I really am not gonna argue about this anymore so shoved it in.