LP1981628 Third follow-up

LP1981628 Third follow-up

The last follow-up had the inadvertent side-effect of hiding the
message directing the patron to contact their library if they had a
negative balance. My thought is that if there are negative bills then
the patron should see the alert to contact their library about them
regardless of whether or not online payments are allowed. So, this
additional followup separates that alert from the myopac_cc_allowed logic.

This also makes some minor display tweaks to the BooPAC:
- Applies the Bootstrap 'alert-warning' to the negative bills message
in the BooPAC.
- Adds a page header.
- Changes the styling and wording of the grocery charges heading to match
the circulation charges heading.
- Changes the styling of the grocery and circulation tables to be
consistent with each other.

Signed-off-by: Terran McCanna <tmccanna@georgialibraries.org>