chore(docs): update Sphinx to 1.3.1

Author: mboersma

dev_requirements.txt

@@ -8,7 +8,7 @@ termcolor==1.1.0
 git+https://github.com/pyinstaller/pyinstaller@7413317
 
 # Deis documentation requirements
-Sphinx==1.3.0
+Sphinx==1.3.1
 smartypants==1.8.6
 sphinxcontrib-httpdomain==1.3.0