Scheduled weekly dependency update for week 50 (#243)

* Update pytest-aiohttp from 0.2.0 to 0.3.0

* Update aiohttp from 2.3.5 to 2.3.6

* Update yarl from 0.15.0 to 0.16.0

Author: pyup.io bot

requirements-dev.txt

@@ -7,11 +7,11 @@ aioredis==1.0.0
 cryptography==2.1.4
 docker-py==1.10.6
 pynacl==1.2.1
-pytest-aiohttp==0.2.0
+pytest-aiohttp==0.3.0
 pytest-cov==2.5.1
 pytest-mock==1.6.3
-aiohttp==2.3.5
+aiohttp==2.3.6
 multidict==3.3.2
 chardet==3.0.4
-yarl==0.15.0
+yarl==0.16.0
 aiomcache==0.6.0