Drop 'setup.py test'. Just use 'runtests.py'.
Add pinned versions of wheels and mkdocs to our dev requirements.
Merge pull request #2314 from tomchristie/drop-setup-py-test

Drop 'setup.py test'. Just use 'runtests.py'.
YAML encoder fix for 3.0 serializers.
Merge pull request #2315 from tomchristie/yaml-encoder-fix

YAML encoder fix for 3.0 serializers.
Merge master