Make coordinate 'frames' be imported
Test for BaseCoordinateFrame instead of SphericalCoordinatesBase
Remove builtin_systems, coordsystems, and old_builtin_systems_names modules
Fix VO conesearch to comply with APE5 coordinate API
Change remaining refs to builtin_systems to builtin_frames
Merge pull request #15 from taldcroft/coordinates-ape5-frames-integration

Coordinates APE5 frames integration with the rest of astropy