vdscli: drop Windows support

In prehistorical ages, Engine used to run on Windows, and vdsClient
could be installed there. This is no longer the case, and there is no
reason to carry this baggage any longer.

Change-Id: I9081fea11d7e7e8b48c32cb3babbb5070f2e04e0
Signed-off-by: Dan Kenigsberg <danken@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/28675
Reviewed-by: Yaniv Bronhaim <ybronhei@redhat.com>
Reviewed-by: mooli tayer <mtayer@redhat.com>