Move ROS-dependent packages from rtt_geometry to rtt_ros_integration (cleanup of #11)

> This PR includes changes from https://github.com/orocos/rtt_ros_integration/pull/10 and adds rtt_tf to rtt_ros_integration so that rtt_geometry can only depend on the orocos toolchain and KDL.

> Note that it is removed from rtt_geometry in https://github.com/orocos/rtt_geometry/pull/8.

Recreating #11 with pruned empty commits from rtt_geometry. Added packages rtt_tf and rtt_kdl_conversions, following the discussions in #11.

The result is equivalent to https://github.com/jhu-lcsr-forks/rtt_ros_integration/commit/669ad93fe614ab9e9eb6466057f5f7416641fae3 from #11 without the last commit which removed rtt_kdl_conversions again.