[ENH] Add post_snippet as post_content is not available anyway to post create snippet


git-svn-id: file:///var/local/code.tiki.org/tikisvn/trunk@52634 b456876b-0849-0410-b77d-98878d47e9d5
[ENH] Tiki Addons: allow adding of custom css as part of addon


git-svn-id: file:///var/local/code.tiki.org/tikisvn/trunk@52635 b456876b-0849-0410-b77d-98878d47e9d5