Enforce two blank lines after def/class definition

Closes #311
diff --git a/CHANGELOG b/CHANGELOG
index 54ac591..5b85e4d 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -11,6 +11,8 @@
   line, which seems logical.
 - It's not really more readable to split before a dictionary value if it's part
   of a dictionary comprehension.
+- Enforce two blank lines after a function or class definition, even before a
+  comment. This is related to PEP8 error E305.
 
 ## [0.12.2] 2016-10-09
 ### Fixed