virt: Add gracefunlly or kill_vm_before_test

Signed-off-by: Li Yang <liyang.fnst@cn.fujitsu.com>
Merge pull request #927 from liyangfnst/kill_vm

virt: Add timeout and gracefunlly or kill_vm_before_test
adding qemu sandboxing option

Adding new command line argument to "./run" script: "-s,--qemu_sandbox".
It enables the Qemu command line argument "-sandbox on", running all
tests with the system call filter turned on.

Signed-off-by: Eduardo Otubo <otubo@linux.vnet.ibm.com>
qemu.test.virtual_nic_send_buffer: Some modification

Make file transfer support tcp, udp or both.
Add netperf_udp burst test
ignore errors when deleting the test file on host and guest.

Signed-off-by: Yunping Zheng <yunzheng@redhat.com>