fill in postgres application_name on connection

* Tried to fill in application_name in awx/__init__.py but I think that
is too late
* Fill in database application_name with enough information to easily
trace the connection from postgres back to the node and pid that
initiated the connection.
* Set application_name in django settings so that application_name is
set _before_ the first postgres connection is established.

awx/main/management/commands/check_migrations.py

@@ -8,5 +8,7 @@ class Command(MakeMigrations):
     def execute(self, *args, **options):
         settings = connections['default'].settings_dict.copy()
         settings['ENGINE'] = 'sqlite3'
+        if 'application_name' in settings['OPTIONS']:
+            del settings['OPTIONS']['application_name']
         connections['default'] = DatabaseWrapper(settings)
         return MakeMigrations().execute(*args, **options)

awx/settings/development.py

@@ -184,3 +184,6 @@ else:
         pass
 
 AWX_CALLBACK_PROFILE = True
+
+if 'sqlite3' not in DATABASES['default']['ENGINE']: # noqa
+    DATABASES['default'].setdefault('OPTIONS', dict()).setdefault('application_name', f'{CLUSTER_HOST_ID}-{os.getpid()}-{" ".join(sys.argv)}'[:63]) # noqa

awx/settings/production.py

@@ -102,6 +102,7 @@ except IOError:
     else:
         raise
 
+# The below runs AFTER all of the custom settings are imported.
 
 CELERYBEAT_SCHEDULE.update({  # noqa
     'isolated_heartbeat': {
@@ -110,3 +111,5 @@ CELERYBEAT_SCHEDULE.update({  # noqa
         'options': {'expires': AWX_ISOLATED_PERIODIC_CHECK * 2},  # noqa
     }
 })
+
+DATABASES['default'].setdefault('OPTIONS', dict()).setdefault('application_name', f'{CLUSTER_HOST_ID}-{os.getpid()}-{" ".join(sys.argv)}'[:63]) # noqa