[FIX]Fix the description of the option, since "Visible by administrators only" allows users to view the field at item creation time, but not after the item is created.

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@48407 b456876b-0849-0410-b77d-98878d47e9d5
[FIX] Changes added to fix Switching themes feature not working for anonymous users Ref: http://dev.tiki.org/item4874

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@48408 b456876b-0849-0410-b77d-98878d47e9d5