LP#1879983: new table and seed data for curbside

LP#1879983: new table and seed data for curbside

This patch adds a new database table, action.curbside, for
tracking appointments to pick up on-shelf hold requests:

 id             - ID
 patron         - patron that the appoint is for
 org            - pickup library that the appointment is for
 slot           - date and time of appointment
 staged         - whethers for appointment have been staged
 stage_staff    - staff member responsible for staging the items
 arrival        - whether patron has arrived to pick up the items
 delivered      - whether items have been checked out to patron
 delivery_staff - staff member responsible for checking out the items
 notes          - notes about the appointment, e.g., the color
                  of the patron's vehicle

It also adds four new library settings:

* circ.curbside: whether to enable curbside appointments for
  picking up available hold requests. This default to off.

* circ.curbside.granularity: interval between appointment slots. This
  defaults to 15 minutes.

* circ.curbside.max_concurrent: how many appointments to permit per
  time slot.  This defaults to 10.

* circ.curbside.disable_patron_input: if turned on, display scheduled
  and pending appointments in My Account in the public catalog but
  do not give the patron the ability to change them from My Account.
  This defaults to false, i.e., allowing patrons to modify appointments
  from My Account.

It also adds two Action Trigger hooks:

* hold.offer_curbside: to trigger notifications offering a patron the
  opportunity to set an appointment time; this is invoked if the
  CurbsideSlot A/T reactor is used to create appointment slots when
  holds become available.

* hold.confim_curbside: fired when a curbside pickup appointment is
  created or updated.

It also adds seed data for the Curbside A/T validator and CurbsideSlot A/T
reactor.

Finally, it adds sample A/T event definitions:

* Curbside offer Email notification
* Curbside offer SMS notification
* Curbside confirmation Email notification
* Curbside confirmation SMS notification

These event definitions are disabled by default.

In addition to Mike Rylander, significant contributions to this
patch were made by Jason Boyer and Galen Charlton.

Sponsored-by: PaILS
Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>
Signed-off-by: Mike Rylander <mrylander@gmail.com>
Signed-off-by: Jason Boyer <jboyer@equinoxinitiative.org>