CHANGELOG: []byte(nil) is treated as NULL

CHANGELOG.md

@@ -5,6 +5,7 @@ Changes:
   - Go-MySQL-Driver now requires Go 1.1
   - Connections now use the collation `utf8_general_ci` by default. Adding `&charset=UTF8` to the DSN should not be necessary anymore
   - Made closing rows and connections error tolerant. This allows for example deferring rows.Close() without checking for errors
+  - `byte(nil)` is now treated as a NULL value. Before it was treated like an empty string / `[]byte("")`.
   - New Logo
   - Changed the copyright header to include all contributors
   - Optimized the buffer for reading