Merge pull request #230 from botstory/pyup-update-pytest-3.1.0-to-3.1.1

Update pytest to 3.1.1

requirements.txt

@@ -1,6 +1,6 @@
 aiohttp==2.1.0
 motor==1.1
-pytest==3.1.0
+pytest==3.1.1
 pytest-aiohttp==0.1.3
 pytest-asyncio==0.5.0
 pytest-catchlog==1.2.2