Add changelog entry for v1.4.0 (uber-go#429)

Add a changelog entry for the 1.4.0 minor release.

CHANGELOG.md

@@ -1,5 +1,17 @@
 # Changelog
 
+## v1.4.0 (12 May 2017)
+
+This release adds a few small features and is fully backward-compatible.
+
+Enhancements:
+
+* [#424][]: Add a `LineEnding` field to `EncoderConfig`, allowing users to
+  override the Unix-style default.
+* [#425][]: Preserve time zones when logging times.
+* [#431][]: Make `zap.AtomicLevel` implement `fmt.Stringer`, which makes a
+  variety of operations a bit simpler.
+
 ## v1.3.0 (25 Apr 2017)
 
 This release adds an enhancement to zap's testing helpers as well as the
@@ -200,3 +212,6 @@ upgrade to the upcoming stable release.
 [#402]: https://github.com/uber-go/zap/pull/402
 [#415]: https://github.com/uber-go/zap/pull/415
 [#416]: https://github.com/uber-go/zap/pull/416
+[#424]: https://github.com/uber-go/zap/pull/424
+[#425]: https://github.com/uber-go/zap/pull/425
+[#431]: https://github.com/uber-go/zap/pull/431