Bench: Standalone Mode external services.

Currently, running oceanbench in standalone mode defaults to using the production versions of oceantv and oceancron, however, most of the time when testing in standalone mode we don't want to be touching any external data (hence the name standalone).

Whilst you can set a different tvurl or cronurl, I think that the default case should be to mock sending the normal requests, and then perhaps just saving the crons and broadcasts in oceanbench's local filestore. Otherwise, when running oceanbench on its own, you can save a broadcast, but then you cannot access the saved broadcast since it is not being saved in the correct store.