update distance_field API to no longer use geometry_msgs

This is a stepping stone on the way to #215. The distance_field API currently uses geometry_msgs::Pose, which it internally converts to an Eigen::Affine3d. collision_detection::World stores the poses as Eigen::Affine3d already, and then passes them through the notification system as such. Thus, we convert eigen -> geometry_msgs -> eigen every time an object is updated/moved/etc.

I can't find much code out there depending on the DistanceField API, but I marked as deprecated with an intent to remove these calls in Jade. I've already updated the tests to use the new API, and will also be updating the SBPL wrapper to use the new API before I get to opening a PR on that.