Noted added error handler

#20

Author: bcomnes

CHANGELOG.md

@@ -3,6 +3,9 @@ All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/).
 This change log adheres to standards from [Keep a CHANGELOG](http://keepachangelog.com).
 
+## Unreleased
+* Handle error when release number already exists on github
+
 ## [1.1.2] - 2015-03-09
 * add `dry-run` and `workpath` options
 * add a `get-defaults.js` test