Add python tool for load trajectories from param server (ros ticket #4014)

[ahendrix]

look at joint_trajectory_action_tools for a method already implemented

trac data:

• Owner: sglaser
• Reporter: mwise
• Reported at: Mon Mar 15 17:02:53 2010
• URL: https://code.ros.org/trac/wg-ros-pkg/ticket/4014