netinfo: Displays active slave for the bond in getVdsCaps
vdsmapi-schema: Adding Active slave support
networkTests: Test to check if active slave exists

Adding active slave field for the bond in the getVdsCaps
Adding active slave in vdsmapi-schema.json
Displays an active slave if exists or displays '' when there is no active slave

Change-Id: Ib6c40755c361523a28cbd68af110e3b20cb9ae25
Signed-off-by: Genadi Chereshnya <gcheresh@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/32915
Reviewed-by: Piotr Kliczewski <piotr.kliczewski@gmail.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>