Various MoveIt improvements

[alexvannobel]

This PR addresses a couple of issues that were reported to us mainly by email to [email protected] about the Kortex pre-computed trajectories action server.
In details:

• Sometimes the server would reject very short trajectories by saying the arm already reached the point, but it wasn't true.
• Sometimes a notification mismatch would happen in the action server because it would receive the ACTION_PREPROCESS_END notification after the ACTION_START notification. This behaviour is not fixed in the arm's firmware (as of v2.0.1), but we added a case where the state machine would simply ignore this mismatch instead of failing the trajectory.
• Sometimes the server would report a fail for a very short trajectory when in fact the arm wasn't done validating. As the arm needs to validate every precomputed trajectory, the overhead of sending the trajectory and getting the response back was longer than executing it and that's why MoveIt considered it failed. The MoveIt config's have been adapted to timeout after a longer delay.

Unrelated to MoveIt:

• It is now possible to pass the username and password of the Kortex user session in kortex_driver.launch. The default values are "admin" and "admin" (they were previously hardcoded in the C++ driver).