Moves the version information to a seperate file. This is mostly due to
import cycle errors occuring when using "import
github.com/kubernetes/kompose/cmd" in order to get the global variable
of VERSION and GITCOMMIT.
Update's the Makefile and other files accordingly.
If the version and commmit is unretriveable due to not being able to
find the kompose binary, the one from pkg/version/version.go will be
used.
