because it causes a runtime panic if a binary which has its own implementation
of "-version" flag tries to reuse a package library which indirectly depend on
"pkg/version".
e.g. If such an user-defined binary tires to link "pkg/api" or "pkg/client",
the binary fails with a runtime panic "flag redefined: version".
Tested: Passed -version argument to kubelet (and all other binaries):
$ output/go/bin/kubecfg -version
Kubernetes version 0.1, build 6454a541fd56
Signed-off-by: Filipe Brandenburger <filbranden@google.com>
