In checkHNname command, implement the CRAB-like mode.

The standalone mode was already implemented. I now implemented a CRAB-like, where what I do is to use the self.myproxy object to call getHyperNewsName(). Not sure if this makes sense though.
For issue #4141 
Just to note that we no longer need this. Since we now except any instance name given by the user, if the instance is not in the SERVICE_INSTANCE, we regard it as a serverl url. 
Thought you can merge it just fine