Add collision avoidance packages

This branch incorporates the collision_avoidance_pick_and_place package which is based on the original pick and place package with the collision avoidance capability.
Also, a new ur5_collision_avoidance_moveit_config package was created to support the collision avoidance pick and place demo.  This package is similar to the existing moveit config package but it incorporates sensor data and a allowed collision map that takes the new urdf elements into account.