Add 2.17.0-beta.4 to CHANGELOG

[ci skip]

(cherry picked from commit 96671cb)

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Ember Changelog
 
+### 2.17.0-beta.4 (October 30, 2017)
+- [#15746](https://github.com/emberjs/ember.js/pull/15746) [BUGFIX] Fix computed sort regression when array property is initally `null`.
+- [#15777](https://github.com/emberjs/ember.js/pull/15777) [BUGFIX] Fix various issues around accessing dynamic data within a partial.
+
 ### 2.17.0-beta.3 (October 23, 2017)
 - [#15606](https://github.com/emberjs/ember.js/pull/15606) [BUGFIX] Add fs-extra to deps
 - [#15697](https://github.com/emberjs/ember.js/pull/15697) [BUGFIX] Move accessing meta out of the loop