[MOD]Improve readability of notification message (first content, later dates and unscrubscribe url, etc)

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@50193 b456876b-0849-0410-b77d-98878d47e9d5
[FIX]Add user as default value in the author field to prevent permission issues saving articles while leaving empty that fied

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@50195 b456876b-0849-0410-b77d-98878d47e9d5