Renamed strands_upper_body_detector to upper_body_detector
strands_perception_people_launch is now called perception_people_launch
changed python_distribute installer URL

This is taken from http://www.gossamer-threads.com/lists/python/python/1158958 where Pierrick posted this solution
Renamed pedestrian_tracker launch files
Merge branch 'hydro-devel' of https://github.com/strands-project/strands_systems into ppl_rename
Merge pull request #80 from cdondrup/ppl_rename

Renaming pedestrian tracker