Scheduled weekly dependency update for week 38 (#504)

* Update sphinx from 1.7.9 to 1.8.1

* Update tox from 3.2.1 to 3.4.0

* Update pytest from 3.8.0 to 3.8.1

* Update sqlalchemy from 1.2.11 to 1.2.12

Author: pyup.io bot

requirements.txt

@@ -4,12 +4,12 @@ ipdb==0.11
 ipython==6.5.0
 flake8==3.5.0
 -e .[sa]
-sphinx==1.7.9
-tox==3.2.1
-pytest==3.8.0
+sphinx==1.8.1
+tox==3.4.0
+pytest==3.8.1
 pytest-cov==2.6.0
 pytest-sugar==0.9.1
 pytest-timeout==1.3.2
 sphinxcontrib-asyncio==0.2.0
-sqlalchemy==1.2.11
+sqlalchemy==1.2.12
 psycopg2==2.7.5