Bumped version to v2.2.2, added CHANGELOG entry

CHANGELOG.md

@@ -5,6 +5,17 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 (modification: no type change headlines) and this project adheres to 
 [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## [2.2.2] - 2019-12-17
+**MuirGlacier** support by updating to the new difficulty formula as stated
+in [EIP-2384](https://eips.ethereum.org/EIPS/eip-2384).
+
+Please note that this release does not contain all the changes merged into
+master since the `v2.2.0` release and only backports the difficulty formula 
+adjustments to support MuirGlacier without having to go through migration to 
+the `v3.0.0` which contains breaking changes.
+
+[2.2.2]: https://github.com/ethereumjs/ethereumjs-block/compare/v2.2.1...v2.2.2
+
 ## [2.2.1] - 2019-11-14
 **Istanbul** support by updating to the most recent `ethereumjs-tx` version
 [v2.1.1](https://github.com/ethereumjs/ethereumjs-tx/releases/tag/v2.1.1).

package.json

@@ -1,6 +1,6 @@
 {
   "name": "ethereumjs-block",
-  "version": "2.2.1",
+  "version": "2.2.2",
   "description": "Provides Block serialization and help functions",
   "main": "index.js",
   "files": [