Cache serialised services in Redis

Same as we’re doing for templates.

This means avoiding a database call, even for services that don’t hit
our API so often.

They’ll still need to go to the database for the API keys, because we’re
not comfortable putting the API key secrets in Redis.

But once a service has got its keys from the database we commit the
transaction, so the connection can be freed up until we need it again to
insert the notification.

app/serialised_models.py

@@ -128,16 +128,17 @@ class SerialisedService(SerialisedModel):
     @classmethod
     @memory_cache
     def from_id(cls, service_id):
-        return cls(cls.get_dict(service_id))
+        return cls(cls.get_dict(service_id)['data'])
 
     @staticmethod
+    @redis_cache.set('service-{service_id}')
     def get_dict(service_id):
         from app.schemas import service_schema
 
         service_dict = service_schema.dump(dao_fetch_service_by_id(service_id)).data
         db.session.commit()
 
-        return service_dict
+        return {'data': service_dict}
 
     @cached_property
     def api_keys(self):