[ci skip] Fix 3.1.4 release date ...

Apparently, I'm from the future.
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index d7418ff..209193b 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -11,7 +11,7 @@
 Version 3.1.4
 =============
 
-Release Date: March 23, 2017
+Release Date: March 20, 2017
 
 -  **Security**