Prepare 3.1.3 release

Conflicts:
	CHANGES.txt
	supervisor/version.txt

CHANGES.txt

@@ -8,8 +8,8 @@
 - Environment variables are now expanded for all config file options.
   Patch by Dexter Tad-y.
 
-3.1.3 (Next 3.x Release)
-------------------------
+3.1.3 (2014-10-28)
+------------------
 
 - Fixed an XML-RPC bug where the ElementTree-based parser handled strings
   like ``<value><string>hello</string></value>`` but not strings like