vnfs: Enable PVP using vhost-user

vnfs: Enable PVP using vhost-user

Enable booting of a VM with DPDK and run testpmd for
PVP testing.
* Added throughput and back2back tests with pvp deployment scenario in
  01_testcases.conf
* PVP requires DPDK 2.0 with VHOST_USER enabled and QEMU 2.2.0
* Tested on CentOS7 and Fedora 20
* Fix conflict with change 1078

Recent Changes:
* Fix merge conflict (testcase.py and testcases.conf)
* Remove QEMU_DIR. User must set QEMU_BIN
* Set bidir traffic to True
* Add flow for bi-directional traffic
* Use working OVS_TAG ad2e649834be20dd01b1632799fe778106a96a2d
* Merge change 1096 (src: Add QEMU makefile)
* Set virtio-net-pci csum=off and other variables to off
* Move hardcoded values to conf/*

JIRA: VSPERF-56

Change-Id: I4ad184531064855493483d9833a7722c9f7d3576
Signed-off-by: Madarang, Dino Simeon <dino.simeonx.madarang@intel.com>
Signed-off-by: Meghan Halton <meghan.halton@intel.com>
Reviewed-by: Billy O Mahony <billy.o.mahony@intel.com>
Reviewed-by: Maryam Tahhan <maryam.tahhan@intel.com>
Reviewed-by: Martin Klozik <martinx.klozik@intel.com>