Provide a utility for finding and setting the best mesh channel troop-wide

[jingman]

I'd imagine it working something like this...

Run mesh.optimizechannel and the whole Troop works together to collect rssi values and find the channel that seems to provide the best connection. Probably easiest to just average all the rssi values for a given channel, but that wouldn't account for outliers and exceptions. When the best channel is found, a command goes out to all the Scouts that changes them all to the new channel.