update pytest-cov and coverage to repair coveralls

Author: agriffis

requirements/testing.txt

@@ -3,4 +3,3 @@ mock==1.0.1
 pytest==2.8.3
 pytest-django==2.9.1
 pytest-xdist==1.13.1
-pytest-cov==2.2.0

tox.ini

@@ -17,7 +17,15 @@ commands=python runtests.py -q --cov oauth2_provider --cov-report= --cov-append
 deps =
     django18: Django==1.8.11
     django19: Django==1.9.4
-    coverage<4
+    coverage==4.1
+    pytest-cov==2.3.0
+    -rrequirements/testing.txt
+
+[testenv:py32-django18]
+# coverage-4.1 doesn't support python-3.2.
+commands=python runtests.py -q
+deps =
+    django18: Django==1.8.11
     -rrequirements/testing.txt
 
 [testenv:docs]