Split the netperf run script into 3 ones so that it can be used more easily
in an automated run.
netperf.run - use native nic driver (x86) or usb2.0 (arndale, panda)
netperf_usb30.run - use native nic driver (x86) or usb3.0
netperf_bridge.run - use native nic driver (x86) or usb3.0 (arndale) and bridge
Issue #794
