Registry tool: Use global flags for config create

[theganyo]

If a user specifies any of flags that set a stored value during config create, the created config should save them. Eg.

  --registry.address string    the server and port of the registry api (eg. localhost:8080)
  --registry.insecure          if specified, client connects via http (not https)
  --registry.location string   the registry location
  --registry.project string    the registry project