Merge branch 'master' into improve_cosmology_use

CHANGELOG.md

bilby/core/prior.py

bilby/core/result.py

bilby/core/sampler/cpnest.py

bilby/core/sampler/emcee.py

bilby/core/sampler/ptemcee.py

bilby/gw/detector.py

bilby/gw/likelihood.py

bilby/gw/source.py

bilby/gw/utils.py

containers/Dockerfile-test-suite-python27

containers/Dockerfile-test-suite-python37

examples/injection_examples/roq_example.py

setup.py

test/gw_likelihood_test.py

test/result_test.py