Merge branch 'clean-up-default-priors' into 'master'

bilby/gw/prior.py

bilby/gw/prior_files/GW150914.prior

bilby/gw/prior_files/GW170817.prior

bilby/gw/prior_files/aligned_spins_binary_black_holes.prior

bilby/gw/prior_files/aligned_spins_waveform_tides_off.prior

bilby/gw/prior_files/aligned_spins_waveform_tides_on.prior

bilby/gw/prior_files/binary_neutron_stars.prior

bilby/gw/prior_files/precessing_binary_neutron_stars.prior

.../gw/prior_files/precessing_spins_binary_black_holes.prior

.../gw/prior_files/precessing_spins_waveform_tides_off.prior

...y/gw/prior_files/precessing_spins_waveform_tides_on.prior

test/gw_prior_test.py

test/prior_files/aligned_spins_waveform_tides_on.prior

test/prior_files/binary_neutron_stars.prior

test/prior_files/precessing_spins_binary_black_holes.prior

test/prior_test.py