Bug 17006: Add /patrons/{patron_id}/password

Bug 17006: Add /patrons/{patron_id}/password

This patch introduces an endpoint for changing a patron's password. It
targets privileged user with the right permissions, changing some
patron's password.

To test:

- Apply this patchset
- Run:
  $ kshell
 k$ prove t/db_dependent/api/v1/patrons_password.t
=> SUCCESS: tests pass!
- Play with the different use cases highlighted by the tests, on your
favourite REST testing tool (Postman, RESTer on FF, etc).

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>