upgrade: vdsm-jsonrpc needs to obsolete vdsm-api

vdsm-api was removed during jsonrpc implementation and now we need to
make sure that it is removed when we upgrade from older version.

Bug-Url: https://bugzilla.redhat.com/1140694
Change-Id: Id5ca0f4d4f8975b3b01ec740341834877eb6ca09
Signed-off-by: pkliczewski <piotr.kliczewski@gmail.com>
Reviewed-on: http://gerrit.ovirt.org/32858
Reviewed-by: Dan Kenigsberg <danken@redhat.com>