[#6431] ticket:430 Upgrade to ming 0.4.x to avoid extraneous count() queries
[#6431] ticket:430 Fix possible count() call on list
[#6431] don't rely on bool(cursor)

* bool(cursor) is not good either
* refactor some attachment methods up to (Versioned)Artifact
* User.withskill len fix
[#6431] Fix places that were still expecting a cursor

Signed-off-by: Tim Van Steenburgh <tvansteenburgh@gmail.com>
[#6431] bump ming version to get aggregate() method
[#6431] bump timermiddleware for compatibility with new ming (when debug logging)