SEATTLE (Reuters) – Microsoft Corp said on Tuesday it appointed Mason Morfit, president of activist investor ValueAct Capital, as a board member. The worlds largest software company offered Morfit a board seat in August, following months of lobbying by ValueAct for a say on how Microsoft is run. Under the agreement struck last summer, Morfit had the option of joining the board at the first quarterly board meeting after Novembers annual shareholder meeting. ValueAct bought a $2 billion stake in Microsoft last April and immediately began agitating for change. …