Fixes #163
fixes #163
Fixes #156

Added a helper method grabbing only the uses requiring delivery
of JPEG resoures.  From now on, patrons can request other resolutions
and formats in the special instructions fields, but we are hoping
to eliminate erroneous TIF requests with this change.
adding helper function to get SOME intended uses
finishing fix to #156

There is a known issue here, to be addressed soon.
The javascript on this page is not firing on selection of an
intended use value.  I suspect the change in jquery is responsible,
but need more time to analyze the problem.
Adding suggested workaround for active admin bug.

see http://bit.ly/Iin4pr for the issue and approaches to
patching the system.