Adding with_jsonrpc global to spec set default to 1

When this global set to 0, vdsm won't build json related packages that
currently in work in progress state.

Change-Id: I7229fde2263d1add4c0e74aeb7d5d4e0694f3cda
Signed-off-by: Yaniv Bronhaim <ybronhei@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/24033
Reviewed-by: Douglas Schilling Landgraf <dougsland@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>