Adding support for absolute position inputs (GPS/LPS systems)
imu measurement model changed to incorporate imu readings as an absolute measurement when gps data is included
gps test cpp and launch file added
data bag for gps test added
adding seperate launch file for gps localization
Updated robot_pose_ekf test launch files to correct rosbag usage.
robot_pose_ekf: deleted gps_data.bag from source and copied it to pr.willowgarage.com.
Reverted changes to robot_pose_ekf.launch