Possible to start Delta Standalone mode without `DELTA_AUTH` key

[jcace]

It's currently possible to start up delta in --standalone mode without having the DELTA_AUTH key specified. It defaults to just "" in this case, but you can't use any of the cli ex) delta deal make ... because it will fail with DELTA_AUTH env var is required.

I think it would make sense if either a) you can use the cli with a null AUTH key, or b) you can't start the daemon unless DELTA_AUTH is specified