tox/travis maintenance (#4811)

* Use py36 on travis

* Remove basepython from tox

* Use py27 on travis

* Use version ranges for dependencies

* Use tox-travis to sync python/env factors

* Add toxenv/django env vars to codecov build vars

* Use raw string to fix py36 invalid escape sequence

.travis.yml

 language: python
 
 python:
+    - "2.7"
+    - "3.3"
+    - "3.4"
     - "3.5"
 
 sudo: false
 
 env:
-    - TOX_ENV=py27-lint
-    - TOX_ENV=py27-docs
-    - TOX_ENV=py35-django19
-    - TOX_ENV=py34-django19
-    - TOX_ENV=py27-django19
-    - TOX_ENV=py35-django18
-    - TOX_ENV=py34-django18
-    - TOX_ENV=py33-django18
-    - TOX_ENV=py27-django18
-    - TOX_ENV=py27-django110
-    - TOX_ENV=py35-django110
-    - TOX_ENV=py34-django110
-    - TOX_ENV=py27-djangomaster
-    - TOX_ENV=py34-djangomaster
-    - TOX_ENV=py35-djangomaster
-    - TOX_ENV=py36-djangomaster
+    - DJANGO=1.8
+    - DJANGO=1.9
+    - DJANGO=1.10
+    - DJANGO=master
 
 matrix:
     fast_finish: true
+    include:
+      - python: "3.6"
+        env: DJANGO=master
+      - python: "2.7"
+        env: TOXENV="lint"
+      - python: "2.7"
+        env: TOXENV="docs"
+    exclude:
+      - python: "3.3"
+        env: DJANGO=1.9
+      - python: "3.3"
+        env: DJANGO=1.10
+      - python: "3.3"
+        env: DJANGO=master
     allow_failures:
-      - env: TOX_ENV=py27-djangomaster
-      - env: TOX_ENV=py34-djangomaster
-      - env: TOX_ENV=py35-djangomaster
-      - env: TOX_ENV=py36-djangomaster
+      - env: DJANGO=master
 
 install:
-    # Virtualenv < 14 is required to keep the Python 3.2 builds running.
-    - pip install tox virtualenv
+    - pip install tox tox-travis
 
 script:
-    - tox -e $TOX_ENV
+    - tox
 
 after_success:
     - pip install codecov
-    - codecov -e TOX_ENV
+    - codecov -e TOXENV,DJANGO
 
 notifications:
     email: false

rest_framework/__init__.py

-"""
+r"""
 ______ _____ _____ _____    __
 | ___ \  ___/  ___|_   _|  / _|                                           | |
 | |_/ / |__ \ `--.  | |   | |_ _ __ __ _ _ __ ___   _____      _____  _ __| |__

tox.ini

@@ -3,11 +3,17 @@ addopts=--tb=short
 
 [tox]
 envlist =
-       py27-{lint,docs},
        {py27,py33,py34,py35}-django18,
-       {py27,py34,py35}-django19,
-       {py27,py34,py35}-django110,
-       {py27,py34,py35,py36}-django{master}
+       {py27,py34,py35}-django{19,110},
+       {py27,py34,py35,py36}-djangomaster,
+       lint,docs
+
+[travis:env]
+DJANGO =
+    1.8: django18
+    1.9: django19
+    1.10: django110
+    master: djangomaster
 
 [testenv]
 commands = ./runtests.py --fast {posargs} --coverage -rw
@@ -15,26 +21,22 @@ setenv =
        PYTHONDONTWRITEBYTECODE=1
        PYTHONWARNINGS=once
 deps =
-        django18: Django==1.8.17
-        django19: Django==1.9.12
-        django110: Django==1.10.5
+        django18: Django>=1.8,<1.9
+        django19: Django>=1.9,<.1.10
+        django110: Django>=1.10,<1.11
         djangomaster: https://github.com/django/django/archive/master.tar.gz
         -rrequirements/requirements-testing.txt
         -rrequirements/requirements-optionals.txt
-basepython =
-    py36: python3.6
-    py35: python3.5
-    py34: python3.4
-    py33: python3.3
-    py27: python2.7
 
-[testenv:py27-lint]
+[testenv:lint]
+basepython = python2.7
 commands = ./runtests.py --lintonly
 deps =
         -rrequirements/requirements-codestyle.txt
         -rrequirements/requirements-testing.txt
 
-[testenv:py27-docs]
+[testenv:docs]
+basepython = python2.7
 commands = mkdocs build
 deps =
        -rrequirements/requirements-testing.txt