WePay, a startup that’s meant to help take the pain out of managing payments for groups like fraternities and soccer teams, has landed a big new hire: Rasmus Lerdorf, the man who originally created the programming language PHP. Lerdorf, who left Yahoo last November, will be leading development of WePay’s API.  The API will begin rolling out to a small number of developers this summer (you can ask to take part by emailing API@wepay.com ).