Fix csrf-ajax link. Closes #2045
Merge pull request #2050 from jpadilla/issues/2045

Fix csrf-ajax link
Fix some typos and other errors
Merge pull request #2051 from jochenvdv/fix-typos

Fix some typos in contributing.md
Uniqueness constraints imply a forced 'required=True'. Refs #1945
Merge branch 'master' of https://github.com/tomchristie/django-rest-framework
Bring UniqueValidator implementation in line with other uniquness validators.
Update fields.py
#2054: Update exceptions to allow custom detail

This addresses the changes requested in #2054 and allows for custom messages that do not necessarily require a string formatter be present in the detail message.
Merge pull request #2055 from kevinlondon/patch-6

#2054: Update exceptions to allow custom detail
Update html.py
Update html.py
Add PyPI version badge.
Remove test cruft
Remove tests/settings. Using conftest instead.
Reinstate OPTIONS tests
Model fields with .blank or .null now map to required=False. Closes #2017. Closes #2021.
Use select inputs for relationships. Closes #2058.
Split out .create and .update on ListSerializer
Refactor many