removed hardwired version number from phing installation step.
removed hardwired version number from phing installation step.

refs #250
ilios/ilios,stopfstedt/ilios,thecoolestguy/ilios,Trott/ilios,dartajax/ilios,justinchu17/ilios,justinchu17/ilios,Trott/ilios,justinchu17/ilios,thecoolestguy/ilios,ilios/ilios,justinchu17/ilios,dartajax/ilios,stopfstedt/ilios