Active input device variable has update issues with disconnected HDMIs

[eklundjon]

When selecting an HDMI input without an active signal, the device takes too long to respond to the current input query. This causes the ActiveInput device state variable to be clobbered to "Netflix" (oops)

Need to both fix "defaulting" of active input to "Netflix" and correct updating of active input variable when device is slow to respond to queries. This might wind up being the same fix as #6

[eklundjon]

e393786 was only a partial fix. Now input will be "UNKNOWN" instead of "Netflix".