Fix QoS setting to allow IPC

[Myzhar]

Remove default QoS settings and add QosOverridingOptions to allow the node to leverage IPC in composition

Fix #75

[clalancette]

This looks very reasonable to me. The one change I'll ask for is a new launch test that exercises the intra-process comms.

To do that, you can look at the launch tests in e.g. https://github.com/ros/robot_state_publisher/blob/rolling/test/two_links_moving_joint-launch.py (which is exercised by https://github.com/ros/robot_state_publisher/blob/rolling/test/two_links_moving_joint-launch.py).

Thank you.

[Myzhar]

Hi @clalancette
sorry for the late reply. Busy period.
I wanted to finish this PR by adding the test that you asked for, but I have not understood what is required.
I think you posted something wrong in your comment, can you check it?

PS Is there documentation explaining how to create Google test units? I'm not experienced in this area