LP#2043127-Marking org unit as non-visible in the OPAC defaults patrons' preferred...

LP#2043127-Marking org unit as non-visible in the OPAC defaults patrons' preferred pickup locations to the first org unit

Added a check to the OPAC place_hold.tt2 that detects if the patron's
preferred pickup location is missing from the dropdown. If it is, it
adds a default message to the dropdown asking them to choose a pickup
location and chooses it, as well as disabling the submit button and
changing the dropdown color to alert the user.

Steps to test:
[1] Go to Administration -> Server Administration -> Organizational
Units
[2] Select an org unit and uncheck OPAC Visible
[3] Rerun autogen.sh
[4] Find a patron account with that org unit as their home library (it
will also be their preferred pickup library)
[5] Log into that account on the OPAC and attempt to place a hold on a
book
[6] Observe the state of the holds screen

Signed-off-by: Steven Mayo <smayo@georgialibraries.org>
Signed-off-by: Michele Morgan <mmorgan@noblenet.org>