* new cert for gstlalcbc user
 * new default values for gunicorn configuration
 * remove `Labels:` row from superevent table in public-facing view (@roberto.depietri)
 * add a link to return to object page from files page
 * relax annotation throttle for authorized users
 * lots of pre-O4 cert changes
 * test change to improve performance of public view

This is for easy programmatic access to the tier name.

* `auto_increment_insert` updates
* `auto_increment_update` updates
* minor visual tweaks
* enable/disable LVAlert via environment variable
* upstream package updates
* bug fixes and performance improvements

django 2.2.0, django-guardian-2.2.0, new search labels, caching fixes

fixing caching on the dev vm, and testing a five minute
cache for the public alerts page.

The settings for gracedb-playground are no longer on a separate
branch and are just included in master. They can be selected
simply by settings the DJANGO_SETTINGS_MODULE environment variable
appropriately.  This should be much easier to maintain than a
completely separate branch.

Containerized versions of the service will now get their LVAlert
credentials from the environment.  Also add a script for
processing environment variables and starting LVAlert overseer.

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