Update representation with new astropy types.

[WilliamJamieson]

In order to properly implement the fix in astropy/asdf-astropy#181 this list:

asdf-coordinates-schemas/resources/schemas/representation-1.0.0.yaml

Lines 41 to 55 in 533d6ee

	enum:
	- CartesianRepresentation
	- SphericalRepresentation
	- UnitSphericalRepresentation
	- RadialRepresentation
	- PhysicsSphericalRepresentation
	- CylindricalRepresentation
	- CartesianDifferential
	- SphericalDifferential
	- UnitSphericalCosLatDifferential
	- UnitSphericalDifferential
	- SphericalCosLatDifferential
	- RadialDifferential
	- PhysicsSphericalDifferential
	- CylindricalDifferential

needs to be updated with the new terms:

• WGS84GeodeticRepresentation
• WGS72GeodeticRepresentation
• GRS80GeodeticRepresentation