Bump pytest and don't capture logs. Also, show which tests are skipped.

requirements/test.txt

@@ -1,2 +1,2 @@
 case>=1.3.1
-pytest>=3.0,<3.3
+pytest>=3.3

tox.ini

@@ -31,8 +31,8 @@ deps=
 sitepackages = False
 recreate = False
 commands =
-    unit: py.test -xv --cov=celery --cov-report=xml --cov-report term
-    integration: py.test -xsv t/integration
+    unit: pytest -rsx -xv --capture=no --cov=celery --cov-report=xml --cov-report term
+    integration: pytest -rsx --capture=no -xsv t/integration
 setenv =
     WORKER_LOGLEVEL = INFO
     PYTHONIOENCODING = UTF-8