Bug fix---org.conman.uuid() and org.conman.uuid.parse()

For org.conman.uuid(), missing parameters (which I want) cause problems in
some cases, so create the userdata as needed, not at the beginning of the
routine.

Also, for org.conman.uuid.parse(), check the length of the string---if it's
16 bytes, assume a binary version of the UUID, otherwise, parse as normal.