* Adds cached_property decorator, adds feature to move through n discriminators * Adds v3 sample with 2 discriminators * Adds tests of Shape, Tringle, and Quadrilateral traveling through 2 discriminators * Adds test_deserialization.py:test_deserialize_shape * Simplifes XTriangle sample spec schemas * Simplifies Shape schema definition, updates go+python-experimental samples * Fixes python-experimental test_dog tests * Separates off python-experimental spec
* Adds composed model support for allOf oneOf anyOf * Moves discriminator into discriminator() class method, adds test_deserialize_lizard, adds setting discriminator using allOf schema
