/JSON?request=controldevicebyvalue&ref=###&value=#
Control a device given the device's reference number "ref", and value "value". For example, if a light has a value of 0 for off, the following would turn off the device with reference # 3570:
/JSON?request=controldevicebyvalue&ref=3570&value=0
The return is the current JSON formatted status of the device (same return as "getstatus"), or the string "error".