Prepared CHANGELOG for 1.4.0

- Added release date
- Removed empty stub for 1.3.1

Author: weierophinney

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 All notable changes to this project will be documented in this file, in reverse chronological order by release.
 
-## 1.4.0 - TBD
+## 1.4.0 - 2017-03-14
 
 ### Added
 
@@ -21,24 +21,6 @@ All notable changes to this project will be documented in this file, in reverse
 
 - Nothing.
 
-## 1.3.1 - TBD
-
-### Added
-
-- Nothing.
-
-### Deprecated
-
-- Nothing.
-
-### Removed
-
-- Nothing.
-
-### Fixed
-
-- Nothing.
-
 ## 1.3.0 - 2017-03-02
 
 ### Added