Add RQ_QUEUES to default config

We can use string interpolation in the file rather than building it when
making the config. Adding the value to the config allows us to override
it with an environment variable, if we want to (as we do for the UAT
environment).

config/base.ini

@@ -16,6 +16,7 @@ PGUSER = postgres
 PORT=8000
 REDIS_URI = redis://localhost:6379
 REQUIRE_CRLS = true
+RQ_QUEUES = atat_%(ENVIRONMENT)s
 SECRET = change_me_into_something_secret
 SECRET_KEY = change_me_into_something_secret
 SESSION_COOKIE_NAME=atat