Add hardware configuration detection and response

[MattCummings0517]

Various tags may be constructed with differing hardware configurations, so a desirable feature in the software is the ability to probe the tag's hardware to determine which sensors are present and adapt appropriately. Further, if non-essential sensors (e.g. the light sensor or temperature sensor) fail in a tag, the software should allow deployment - ideally first notifying the operator - for example with some rapid flashes of the red LED - but allowing the other sensors to start up and run.

This feature is also quite valuable during test and debug prior to encapsulation.