Make the event view 403 pages more specific (for event views only),
but more generalized (standard message in the template, not taken
from the context).  Also fix up some unit tests which expected the
old behavior.

New API backend which gets a full X509 certificate, verifies it,
and extracts the subject.  To be used in the cloud deployment
with Traefik.

Move a number of scripts which were managed in a separate repo
into management commands.  This way they can be more easily executed
either manually or by cron jobs.

Settings have been reorganized and how different parameters are
determined has been reworked to be compatible with both a Puppet-based
VM deployment and a containerized deployment

Add some information to VOEvents and rearrange some things:
  * Add EM Bright information (BNS, NSBH, BBH, Terrestrial) in a
    Group in the What section
  * Put ProbHasNS and ProbHasRemnant in a Group and rename to 'HasNS'
    and 'HasRemnant'

See https://git.ligo.org/lscsoft/gracedb/issues/77

Change the Retraction field to be an int (rather than a bool)
to match other "flag-type" parameters.

Since we only have one API endpoint now, we only need one skymap
URL in a VOEvent, rather than three.

Also removes need for pylal, which is no longer available.