Add water mining/extraction power requirements

[davedx]

From http://www.thespacereview.com/article/3479/1:

"five kilowatt-hours to mine 4,150 kilograms of water ore. The 7.5-kilowatt-hour examples from the NASA study were then used for power estimates of the separation and vitalization processing to produce 33 kilograms of refined pure quality water from the mined Martian water-bearing regolith ore. This gives an energy cost of extracting and processing (with an overhead factor) to produce purified water from Martian raw ore materials at an estimate of about 230 watts per kilogram."