war/WEB-INF/web.xml ---add the url API/potential/potential to it.
src/API/potential/area.java ---just remove two unused variable
API/potential/potential.java ---the given values were wrnog(shiftLat shiftLan), fixed.
---update GAE SDK
API/potential/Area.java ---new class for storing area(because storing on datastore may delay)
API/potential/area.java->buildArea ---just rename the name and modified maxProfit->targetMaxProfit
API/potintial/potential.java ---rewrite the code!!!!!!(*****have not finish debugging*****)