Scheduled weekly dependency update for week 12 (#141)

* Update pytest from 3.4.2 to 3.5.0

* Update sphinx from 1.7.1 to 1.7.2

* Update cryptography from 2.2 to 2.2.1

* Update aiohttp from 3.0.9 to 3.1.0

requirements-dev.txt

@@ -1,15 +1,15 @@
 -e .
 flake8==3.5.0
-pytest==3.4.2
+pytest==3.5.0
 pytest-cov==2.5.1
 coverage==4.5.1
-sphinx==1.7.1
+sphinx==1.7.2
 pep257==0.7.0
 aiohttp-session==2.3.0
 aiopg[sa]==0.13.2
 aioredis==1.1.0
 hiredis==0.2.0
 passlib==1.7.1
-cryptography==2.2
-aiohttp==3.0.9
+cryptography==2.2.1
+aiohttp==3.1.0
 pytest-aiohttp==0.3.0