comment out a collision planner in hector path follower

[robbiedood]

Dear hector_navigation friends,

We were wondering why the collision_planner_.checkTrajectory in a if statement of hector_path_follower.cpp is commented out reference is here.

So that the for loop would be broken after running one. Hope to hear your expertise.

Best, --Luke

ps: checked the git blame but can not find an answer.