Bug fix and two little features

Two bug fixes, two features 

If a receiver tries to start receiving a link which is does not support, it'll bomb out with an uncaught exception.  I've added a try-catch to catch this and be a bit more descriptive and less "ohmygodtheworldisending"

Also, the receiver: when it prints out it's settings, it previously erroneously displayed the caps in the Jitter Buffer: line.  Now it shows the jitter_buffer, as it should. 

Feature: added the property "client-name" onto the jackaudiosink and jackaudiosrc's in the tx and rx.  It now shows the client name as "openob2", rather than just "python" which is a little undescriptive.  Needed this for my project, as our main server has several openob feeds as well as a couple of other python clients going into jack - needed something a bit more obvious to distinguish them.  

Feature: added the ability to change the autoconnect feature on the jackaudiosink/src's, from the command line, with the option -nja --no-jack-auto.  This changes the connect property to none, rather than auto.  Again, a requirement for my project as I don't want it connecting to the first available sink when the transmitter/receiver starts up.   

I have a feeling that most of these commits will be out of sync with active development, though!