Update Changelog for 0.5.0 release

Changelog

@@ -1,3 +1,24 @@
+v0.5.0
+
+Bump version to 0.5.0
+Add HTMLAnchorElement
+[PR #295] Add one of proptype
+Update the parser to work with the new esprima-fb & ast-types
+[PR #299] Declare prompt function (fixes #204)
+[PR #303] Add String.prototype.endsWith()
+quick fix for react/es6 notation
+extend scope of type params to following bounds
+reasonless shortcut
+Add React.findDOMNode to lib/react.js
+move command documentation into each command
+fix path in --help usage example
+fix predicate filtering of null and undefined
+[PR #292] Types for React synthetic events
+basic support for bounded polymorphism
+infer falsiness
+node haste module support
+add Abnormal.string
+
 v0.4.0
 
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