Add a utility program for listing info about hardware

[jamessynge]

List camera, Arduinos, mount, dome. Print status, port, serial numbers, etc., as appropriate.

[jamessynge]

Wilfred suggested:

FWIW, and regarding comment (#320) above about separate utils for discovering devices, I have mostly been avoiding making the module callable via if __main__ unless they are in the utils folder. However, that would make development a little annoying as you would have to run a util file to test the sensors file. Still, could end up looking something like:

python pocs/utils/devices.py --list_arduinos
python pocs/utils/devices.py --list_cameras
python pocs/utils/devices.py --list_attached_hardware

etc.

[wtgee]

Could also be a part of panoptes/panoptes-tutorials#48