Scheduled weekly dependency update for week 42 (#511)

* Update docker from 3.4.1 to 3.5.1

* Update ipython from 6.5.0 to 7.0.1

* Update tox from 3.4.0 to 3.5.2

* Update pytest from 3.8.1 to 3.9.1

Author: pyup.io bot

requirements.txt

@@ -1,12 +1,12 @@
 coverage==4.5.1
-docker==3.4.1
+docker==3.5.1
 ipdb==0.11
-ipython==6.5.0
+ipython==7.0.1
 flake8==3.5.0
 -e .[sa]
 sphinx==1.8.1
-tox==3.4.0
-pytest==3.8.1
+tox==3.5.2
+pytest==3.9.1
 pytest-cov==2.6.0
 pytest-sugar==0.9.1
 pytest-timeout==1.3.2