updated world file to Gazebo 1.0 sdf format

... using the tool gzsdf from package 'gazebo'
new pkg: joint_state_muxer

moved here from kurtana_joint_state_publisher
load proper package in roslib
add missing dependency to manifest.xml
avz_collada.world: port changes from gazebo_worlds

- finally display ground plane properly
- use stl for collision, dae for visualization