Update aiohttp from 2.1.0 to 2.2.0 (#94)

Author: pyup.io bot

aiohttp_devtools/start/template/requirements.txt

@@ -1,7 +1,7 @@
 # {# This file is special: lines are made unique, stripped and sorted before the new requirements.txt file is created #}
 # you will need to install these requirements with `pip install -r requirements.txt`
 
-aiohttp==2.1.0
+aiohttp==2.2.0
 pytest==3.1.2
 pytest-aiohttp==0.1.3
 pytest-cov==2.5.1