NEW YORK (Reuters) - Stock futures edged up on Friday, erasing earlier losses, after Cyprus agreed with Greece on a takeover of the Greek units of Cypriot banks, which ended uncertainty over the fate of those operations. * Euro zone finance ministers had excluded the Greek branches of Cypriot banks from a controversial tax in the island's international bailout plan, on condition those units would be transferred to Greek banks. * Wall Street was on track to end the week lower, after having advanced for the three previous weeks. The S&P 500 index was off 1 percent for the week so far. ...