Update README.md
Merge branch 'master' of github.com:srl-freiburg/pedsim_ros
minor edits for recording new mixed case data
re-enabling groups
no groups in iros14
improved social activities test scenes, removing ambiguity
tuned standing behaviour to avoid rotations, also incresed queue wait time
minor queueing and standing tune
new airport like scene with different social activities
visually tweaked behaviours in the airport scene