Add CHANGELOG

Source:
https://github.com/reactphp/react/blob/a6de34d61f68adebd3cc3b855268a5f1475749b8/CHANGELOG.md

CHANGELOG.md

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+CHANGELOG
+=========
+
+## 0.4.1 (2014-04-13)
+
+* Bug fix: Check read buffer for data before shutdown signal and end emit (@ArtyDev)
+* Bug fix: v0.3.4 changes merged for v0.4.1
+
+## 0.3.4 (2014-03-30)
+
+* Bug fix: Reset socket to non-blocking after shutting down (PHP bug)
+
+## 0.4.0 (2014-02-02)
+
+* BC break: Bump minimum PHP version to PHP 5.4, remove 5.3 specific hacks
+* BC break: Update to React/Promise 2.0
+* BC break: Update to Evenement 2.0
+* Dependency: Autoloading and filesystem structure now PSR-4 instead of PSR-0
+
+## 0.3.3 (2013-07-08)
+
+???
+
+## 0.3.2 (2013-05-10)
+
+???
+
+## 0.3.1 (2013-04-21)
+
+* Feature: Support binding to IPv6 addresses (@clue)
+
+## 0.3.0 (2013-04-14)
+
+???
+
+## 0.2.6 (2012-12-26)
+
+???
+
+## 0.2.3 (2012-11-14)
+
+???
+
+## 0.2.0 (2012-09-10)
+
+???
+
+## 0.1.1 (2012-07-12)
+
+???
+
+## 0.1.0 (2012-07-11)
+
+* First tagged release