MDL-16348 Reorganise admin tree:

MDL-16348 Reorganise admin tree:
* New Capability report put under Users -> Permissions
* Miscellaneous category renamed to Development
* Unit tests and Functional DB test moved to be under Development.
* The hard-coded hack that was used to change the permission that controls the Backups and stats reports replaced with settings.php files.
* There were two hidden Miscellaneous things in the old category, so I moved them. Multilan upgrade now under Lanuages, and Online assignment cleanup now under Plugins -> Activity modules. Both still hidden.

There was already a way for admin report plugins to control where they appeared in the tree, but it was not documented, so see http://docs.moodle.org/en/Development:Admin_reports