Added drop down comboboxes for configuring ADC inputs to battery and airspeed modules.

This provides the ability to intelligently change the ADCRouting UAVObject directly from the Modules tab. This is a nice improvement, since configuring the ADC input channel is a necessary part of configuring the battery and airspeed modules, as well as future modules down the line.

When an input is taken by another channel, the combobox item is deactivated for the other modules.
![screen shot 2013-07-24 at 3 10 35 pm](https://f.cloud.github.com/assets/1118185/848261/1076650e-f45a-11e2-8784-a462b61f67d2.png)

This helps address the limitation in https://github.com/TauLabs/TauLabs/pull/791.