Update README and CHANGELOG for v0.2.1 release

CHANGELOG

@@ -1,3 +1,10 @@
+v0.2.1 2018-08-19
+
+* Change RWType and FollowResponse to bool and uint8, respectively.
+* Update README with applications using the go-fed/activity library.
+* Update README with links to official implementation reports for go-fed.
+* Add unit test to document behavior when maxDeliveryDepth is set to zero.
+
 v0.2.0 2018-08-04
 
 * Begin FederateAPI unofficial implementation report.

README.md

@@ -20,7 +20,7 @@ documentation for every version of this library.
 
 ## Status
 
-**0.2.0** ([Semantic Versioning](https://semver.org/))
+**0.2.1** ([Semantic Versioning](https://semver.org/))
 
 An [official implementation report](https://activitypub.rocks/implementation-report/)
 was last submitted for version **0.2.0** [here](https://github.com/w3c/activitypub/issues/318).