Update changelog for 0.7.6

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

CHANGELOG.md

@@ -3,9 +3,11 @@ All notable changes to this project will be documented in this file.
 
 ## 0.7.5 – 2017-12-12
 ### Added
-- 
+- Opt-out for external avatars (Gravatar, favicon)
 ### Fixed
-- 
+- Icon scraper warnings
+- Undefined index bugs
+- Draft message active state in message list
 
 ## 0.7.5 – 2017-11-27
 ### Added