Update CHANGELOG for 7.5

CHANGELOG

@@ -12,6 +12,17 @@ v 7.5.0
   - Return valid json for deleting branch via API (sponsored by O'Reilly Media)
   - Expose username in project events API (sponsored by O'Reilly Media)
   - Adds comments to commits in the API
+  - Performance improvements
+  - Fix post-receive issue for projects with deleted forks
+  - New gitlab-shell version with custom hooks support
+  - Improve code 
+  - GitLab CI 5.2+ support (does not support older versions)
+  - Fixed bug when you can not push commits starting with 000000 to protected branches
+  - Added a password strength indicator
+  - Change project name and path in one form
+  - Display renamed files in diff views (Vinnie Okada)
+  - Add timezone configuration to gitlab.yml
+  - Fix raw view for public snippets 
 
 v 7.4.3
   - Fix raw snippets view