Directly pass geometric primitives to FCL

[tobiaskunz]

We should directly pass geometric primitives to FCL instead of converting them to meshes. Currently DART supports box and ellipsoid shapes. URDF supports box, sphere and cylinder. FCL supports all of them and many more except ellipsoids. We should add shapes to DART for sphere and cylinder and pass all of them except ellipsoids directly to FCL.

[saulrh]

In particular, we want to use the half plane primitive for the ground.