Add a searchable dropdown of clinic names to postcode form

uses select2 for the dropdown and a cobrand call to fetch the list of
report titles as the clinic names.
Relies on a redirect in httpd.conf to make the non JS version work.

Still leaves the postcode search in place as select2 won't accept custom
terms if you base it on a select box, which we want to do so it works if
JavaScript is disabled

Fixes #723
Add Cobrand config to include update date in email alerts

This is useful for sites where the updates aren't published on the site
so you need a bit more context in the email alerts.

Add inlude_time_in_update_alerts to default cobrand, off as default
If this is set then the date is added after the name string in the
email, passing in 'alert' as the type to dt_prettify in order to allow
the cobrand to format it accordingly.

This does require pulling out the alert confirmed time from the database
in the send_alerts code where it wasn't before.
Changes to alert-update formatting for ZeroTB

Include date in alerts
Remove everything apart from the update text as we don't need it