virttest.utils_misc: Support url in get_path().

Signed-off-by: Feng Yang <fyang@redhat.com>
virttest.utils_netperf: Add netperf class.

Add netperf class as base class.

Support netperf client in windows guest.

Support install parameter to control whether install netperf or not.

Signed-off-by: Feng Yang <fyang@redhat.com>
virttest.utils_netperf: Update start() function in NetperfClient class

Change to use cmd_output_safe() function.

Signed-off-by: Feng Yang <fyang@redhat.com>
Merge pull request #1721 from FengYang/netperf2

Netperf2