Scheduled weekly dependency update for week 38 (#190)

* Update pytest from 3.7.4 to 3.8.1

* Update pytest-cov from 2.5.1 to 2.6.0

* Update sphinx from 1.7.8 to 1.8.1

* Update aiohttp-session from 2.5.1 to 2.6.0

* Update aiohttp from 3.4.2 to 3.4.4

requirements-dev.txt

@@ -1,18 +1,18 @@
 -e .
 flake8==3.5.0
 async-timeout==3.0
-pytest==3.7.4
-pytest-cov==2.5.1
+pytest==3.8.1
+pytest-cov==2.6.0
 pytest-mock==1.10.0
 coverage==4.5.1
-sphinx==1.7.8
+sphinx==1.8.1
 pep257==0.7.0
-aiohttp-session==2.5.1
+aiohttp-session==2.6.0
 aiopg[sa]==0.15.0
 aioredis==1.1.0
 hiredis==0.2.0
 passlib==1.7.1
 cryptography==2.3.1
-aiohttp==3.4.2
+aiohttp==3.4.4
 pytest-aiohttp==0.3.0
 pyjwt==1.6.4