Improved return codes for public APIs

* Pass True/False back to calling function for better error handling.
* Changed 500 return code description for most common error condition.
* Slight correction to dimming range.
Initial check-in of gop cli app

* Fully functioning CLI app for accessing all current pygop API
features.  Decent error checking and handling.

* Setting on/off and levels as well as printing house info can all be
done in one run of the program.

* Supports using did, device name, rid, and room name to trigger
actions.  Does not support trigging multiple dids/rids/names at this
time, but I don't see that being necessary.