vsperf: Initial integration with VSPERF

vsperf: Initial integration with VSPERF

New scenario class allows to execute vsperf installed inside VM.
Vsperf is executed in trafficgen mode. It means, it will only
configure and execute traffic by external HW traffic generator
based on custom configuration file. After traffic generator stops,
then test results will be converted from vsperf CSV format into
JSON and passed to yardstick for further processing.
Currently, traffic is passed only through external bridge. In
the future, test scenarios will launch VNFs and traffic will
be properly routed to them. Proper routing can be ensured
by OVS flows configuration via setup-script executed during
setup phase.
Testcase definition yaml files inside vsperf/ directory won't be
pushed to the yardstick, but they will be stored inside vsperf
repository. They are part of the draft review only to show
how it is done.

JIRA: VSPERF-288

Change-Id: I13a519ed39091fe89d1a43cc522738044fb3c609
Signed-off-by: Martin Klozik <martinx.klozik@intel.com>
Reviewed-by: <sunshine.wang@huawei.com>
Reviewed-by: <lvjing5@huawei.com>
Reviewed-by: <jean.gaoliang@huawei.com>
Reviewed-by: <david.j.chou@intel.com>