The kubectl version output is very complex and makes it hard for users
and vendors to give actionable information. For example during the
recent Kubernetes 1.4.3 TLS security scramble I had to write a one-liner
for users to get out the version number to give to figure out if they
are vulnerable:

    $ kubectl version | grep -i Server | sed  -n 's%.*GitVersion:"\([^"]*\).*%\1%p'

Instead this patch outputs simply output with `--short`

    ./kubectl version --short
    Client Version: v1.4.3
    Server Version: v1.4.3