[r=axwalk],[bug=1293310] worker/uniter: explicit LookPath for hooks
Go 1.3/tip changes os/exec.Command such that it
conditionally calls LookPath, based on whether or
not the specified path in is absolute. Since this
differs across versions, I have simply changed our
code to explicitly call LookPath all the time.
No tests changed; an existing test failed with Go
tip, and I verified the change fixes it.
Fixes lp:1293310
https://codereview.appspot.com/76780043/