Feature/new scan unifier

This pull request contains the following features:
 - removes the old scan unifier
 - adds the new scan unifier, including the feature of parsing the subscribed topics names from yaml-files
 - adds yaml-files for each robot for the use of scan unifier
 - updates the yaml-file for amcl to use the scan unifier (necessary for the use of three laser scanners for cob4)

tested in simulation. still needs tests on cob4, so please do not merge yet.
sleep is not very good. Can't we use a tf.wait_for_transform?