Allow simple <a> in #control-panel to be default links too

A dropdown menu should *not* be necessary
To enable this, behaviour on clicking a non-tab <a> defined
in a utility function
[student]: Added an 'inbox' to the control panel
preview.initialize makes bloody sure that ..

1. #wide is un-hidden
2. #wide-X is the only visible thing within #wide
Allow clicking of standalone <a> in the control-panel
Changes to track whether *any* scans have been received for an answer-sheet
Re-defined query methods has_scans, gradeable? and publishable?
Generalized query methods received? and graded?

They now take an argument for the extent to which an answer
has graded/received - :none, :partially or :fully ( default )
New class - always-on - to keep all tabs of a non-left ul.nav-tabs enabled
First draft of ability to post/publish individual ..

.. worksheet copies into individual student accounts