Scheduled weekly dependency update for week 35 (#185)

* Update pytest from 3.6.1 to 3.7.4

* Update sphinx from 1.7.5 to 1.7.8

* Update aiopg from 0.14.0 to 0.15.0

* Update cryptography from 2.2.2 to 2.3.1

* Update aiohttp from 3.3.2 to 3.4.2

requirements-dev.txt

@@ -1,17 +1,17 @@
 -e .
 flake8==3.5.0
-pytest==3.6.1
+pytest==3.7.4
 pytest-cov==2.5.1
 pytest-mock==1.10.0
 coverage==4.5.1
-sphinx==1.7.5
+sphinx==1.7.8
 pep257==0.7.0
 aiohttp-session==2.5.1
-aiopg[sa]==0.14.0
+aiopg[sa]==0.15.0
 aioredis==1.1.0
 hiredis==0.2.0
 passlib==1.7.1
-cryptography==2.2.2
-aiohttp==3.3.2
+cryptography==2.3.1
+aiohttp==3.4.2
 pytest-aiohttp==0.3.0
 pyjwt==1.6.4