VirtUtils: be compatible with older libvirt python bindings

Libvirt python API changed between 0.10.2 (F18) and 1.0.5 (F19) and default
parameter value in open() method has been added. This patch makes LNST able
to run without error with older libvirt python bindings.

Signed-off-by: Jan Tluka <jtluka@redhat.com>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
test_tools: make tcp_conn tools more robust and reliable

Major and minor fixes for tcp_conn suite,

* removed unused variables and code cleanup
* server/client processes are terminated in graceful way using shared
  flag instead of sending SIGKILL that left connections in unfinished state
* connection counters are now placed in shared memory instead of
  a variable available to controller only and incremented upon the
  signal delivery

Signed-off-by: Jan Tluka <jtluka@redhat.com>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>