Change CHANGELOG for 1.3.15

[#137170175]

Signed-off-by: Keaty <[email protected]>

CHANGELOG

@@ -4,20 +4,16 @@ v1.3.15 Jan 06, 2017
 * Add new Slack icon to README
   (https://www.pivotaltracker.com/story/show/136438447)
 
-* Update machete to 0.0.56
-
-* Add nginx 1.11.8, remove nginx 1.11.7
+* Add nginx 1.11.8, remove nginx 1.11.6
   (https://www.pivotaltracker.com/story/show/136691285)
+  (https://www.pivotaltracker.com/story/show/136041771)
 
 * Correct copyright NOTICE
   (https://www.pivotaltracker.com/story/show/136141035)
 
 * Add new version warning to staticfile buildpack
   (https://www.pivotaltracker.com/story/show/135234395)
 
-* Add nginx 1.11.7, remove nginx 1.11.6
-  (https://www.pivotaltracker.com/story/show/136041771)
-
 * Use regexes for url_to_dependency mapping for nginx
   - Remove hardcoded version string from url_to_dependency mapping
   (https://www.pivotaltracker.com/story/show/126394939)