hector_object_tracker: renamed hector_object_tracker::param() method to hector_object_tracker::parameter()

This will hopefully fix the build failures on Jenkins for lucid binaries.
See http://jenkins.ros.org/job/ros-fuerte-hector-worldmodel_binarydeb_lucid_amd64/132/console
Merge remote-tracking branch 'origin/master' into catkin
hector_worldmodel: added missing <metapackage/> tag in package.xml