Send fake sensor inputs on loss of sensord connection

Generate proximity not covered event to keep the device from falling
into perpetual proximity blanking state.

Generate ambient light value in normal range, so that display
brightness does not get locked in to extremes.

[mce] Send fake sensor inputs on loss of sensord connection
Do not stop sensors unless the runtime flag is in place
Merge pull request #91 from spiiroin/lost_sensord

Do not leave the device in unresponsive state if sensor inputs are lost