Icmp6Ping: add size option

Signed-off-by: Jan Tluka <jtluka@redhat.com>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Controller: add save_output argument to command

This patch adds "save_output" parameter to the Host API's run method that
will be used to save the command output from a python task in the
following patch.

Signed-off-by: Jan Tluka <jtluka@redhat.com>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
NetTestCommand: save_output implementation for NetTestCommandExec class

This patch enables a user to work with the stdout and stderr from within
the python task after a command is run. A user must state that he's
interested in these outputs by statement similar to following,

res = machine1.run("rpm -qa kernel", save_output="yes")

Later, the outputs can be retrieved by

stdout = res.get_result()["res_data"]["stdout"]
stderr = res.get_result()["res_data"]["stderr"]

This is available for NetTestCommandExec class only.

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