ovs: Configurable arguments of ovs-*ctl

ovs: Configurable arguments of ovs-*ctl

This patch introduces new configuration parameters OVS_OFCTL_ARGS,
OVS_VSCTL_ARGS and OVS_APPCTL_ARGS, which specify default arguments
passed to respective ovs-*ctl tools. So user can specify default
arguments passed to these tools inside configuration file, testcase
parameters or by --test-params option. For example OVS_OFCTL_ARGS
can be modified to use different OpenFlow version by default.

JIRA: VSPERF-567

Change-Id: Ie7448ea94a54b8044af12d0246d66514e057b7dc
Signed-off-by: Martin Klozik <martinx.klozik@intel.com>
Reviewed-by: Al Morton <acmorton@att.com>
Reviewed-by: Christian Trautman <ctrautma@redhat.com>
Reviewed-by: Sridhar Rao <sridhar.rao@spirent.com>
Reviewed-by: Richard Elias <richardx.elias@intel.com>