velodyne release 1.1.0

 * Fix build problems due to PCL 1.7 API incompatibilities (ros-drivers/velodyne#8). This version no longer works with earlier PCL releases.
 * Fix errors with Mac OSX compiler (ros-drivers/velodyne#8).
 * Install pluginlib XML files (ros-drivers/velodyne#9).
 * Install some launch and parameter files.
 * Enable unit tests when CATKIN_ENABLE_TESTING is set (ros-drivers/velodyne#10).