fix 'undefined: version' by running make in cmd/doozer

Right now, make will die like this: 

    make
    go build ./cmd/doozer
    # _/home/fish/dev/doozer/cmd/doozer
    cmd/doozer/doozer.go:118: undefined: version
    make: *** [build] Error 2

Seems that make has to run in cmd/doozer to create 'vers.go'