Lots of failovers seemed to be leaving lots of open connections
to the LVAlert server, so it seems that the connection wasn't being
closed properly. Looks like abort() is the method that should
be called instead of disconnect().

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.

Some of the search utilities were still in the separate
events and superevents apps, so we moved them to the search app
and tried to clean things up a bit.  It's still kind of a mess
and probably not worth doing a full cleanup until we rework
the search.

Failover to lvalert_send now uses new LVALert Python API, rather
than forking a Process to call the lvalert_send script.

All calls to event.graceid() -> event.graceid.

Switch over to new phone alert code (somewhat improved compared
to the old code).  Made a few more updates and bugfixes.

Removing old alert code in alerts.old_alert.  Finished migration
to new code by updating the phone stuff.

Fix "parent" object serialization for event alerts where the
"object" is also an event.  Now provide the subclass for
serialization rather than the base class.

New format for LVAlerts (XMPP alerts).  New class-based
functionality for issuing alerts for events and superevents.
See https://git.ligo.org/lscsoft/gracedb/issues/8.

Reorganized some utility methods in the alerts app, necessitating
some changes to imports in various places.

Moved events.api and superevents.api into the new api app.
We want to have a versioned API, so these are now in
api.v1.events and api.v1.superevents, respectively. Part of this
change is that we require a custom reverse function (api_reverse)
for handling versioning. Much of the required code changes for this
migration include converting reverses to use this function and
changing relative imports appropriately.

Update alert code to determine whether the message should go to
the production, test, or mdc superevent nodes.

Adding serialized label object to label creation and removal
alerts.  This may not be permanent, but some users want this
feature since the object contains a 'self' link which
they use to tell alerts from different servers apart.

Added some utilities for handling signoffs for superevents,
including alerts, labels, logs, etc.

Adding API resource for creating and getting VOEvents from superevents.

Adding EMObservation creation and alerts for superevents.
Note that this required a change to gracedb-client.

Splitting up much of the alerts functionality and
improving/generalizing it.

Instantiating a new alerts app and moving the alert functionality from
events/alert.py to alerts/old_alert.py. This commit forms a starting
point where the old alert functionality is still in place and we can
rework the alert infrastructure to be more modularized, flexible,
and adapted to superevents.