Reduce the use of ignition libraries in RNDF for Drake

[Agustin Alba Chicar]

We need to reduce the use of ignition libraries to a minimum so as to make simpler the integration with Drake's superbuilds.

Current problem:

Ignition libraries are Mercurial based repositories which leads in some problems. Also they are not integrated into the superbuild and are only compatible through Bazel builds.

Current usage:

• loader.cc makes use of both ignition-rndf and ignition-math
• builder makes use of both ignition-rndf and ignition-math
• spline_lane.cc makes use of ignition-math

From the discussion in https://github.com/RobotLocomotion/drake/pull/5932

[Agustin Alba Chicar]

Actually there's a current discussion about this in https://github.com/RobotLocomotion/drake/issues/4542