Need to come up with a solution to allow PowerBlade reversibility.

The problem, is that a load at 10 W one direction measures identically to a load at 0 W the other direction. Put another way, we don't know which direction we are plugged in. However, it is easy to tell the difference with higher wattage loads (~20 watts and up). For example, a 100 watt load plugged in backwards will read -100 W.

One solution that might work for now, is to keep track in FRAM of which direction you are plugged in. If you ever register multiple readings less than -20 watts (or some number like that) make the decision that you are backwards and reverse the real power logic. This will still allow us to detect a 0 W load, as long as the load has previously drawn greater than 20 W.