Check whether Catalyst has a live connection before doing work.

Currently if the Catalyst Python script has Live Vis enabled then DoCoProcessing() is called every time whether or not there is an actual connection for work to be done. This fixes that by checking in RequestDataDescription to see if there is a Live connection first to see if RequestDataDescription() should be called. This is a work-in-progress since it requires a change to how Catalyst Python scripts are generated and I wanted to have a code review on this before making the other changes.