Use correct path for pip cache dir.
Use correct path for pip cache dir.

Plexxi/st2,StackStorm/st2,StackStorm/st2,Plexxi/st2,StackStorm/st2,nzlosh/st2,StackStorm/st2,nzlosh/st2,Plexxi/st2,nzlosh/st2,nzlosh/st2,Plexxi/st2