Scheduled weekly dependency update for week 38 (#104)

* Update pytest-cov from 2.4.0 to 2.5.1

* Update coverage from 4.3.4 to 4.4.1

* Update pytest-aiohttp from 0.1.2 to 0.1.3

requirements-dev.txt

@@ -1,8 +1,8 @@
 -e .
 flake8==3.4.1
 pytest==3.2.2
-pytest-cov==2.4.0
-coverage==4.3.4
+pytest-cov==2.5.1
+coverage==4.4.1
 sphinx==1.6.3
 pep257==0.7.0
 aiohttp-session==1.0.1
@@ -11,4 +11,4 @@ aioredis==0.3.3
 hiredis==0.2.0
 passlib==1.7.1
 aiohttp==2.2.5
-pytest-aiohttp==0.1.2
+pytest-aiohttp==0.1.3