Add changelog entry for author_signature and _source_protocol

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## [unreleased]
+
+### Added
+* Diaspora `author_signature` is now saved to the entity from `comment` and `like` type objects (to `Comment` and `Reaction` instances respectively).
+* Add protocol name to all entities to attribute `_source_protocol`. This might be useful for applications to know which protocol payload the entity was created from once multiple protocols are implemented.
+
 ## [0.10.1] - 2017-03-09
 
 ### Fixes