Better user hints if no pairing available

[pollockm]

If I create a configuration with just one of these modules defined (and thus no second module to pair with), the module configuration gives me no hints that I need to create another module for it to be useful.

I expect (at minimum) the module to appear 'broken' with a message saying it needs to be paired with another UDP module to function. If there are no paired modules available, I expect to see a message to that effect instead of an empty Pairing Options table. I should also either see the Pair Module button greyed out or be invisible in this case.