Fix version number migration from semver

**As a** developer 
**In order to** follow known best practices 
**I wanted** the gem version numbering to be [semantic versioning](http://semver.org/) 

However,
**I order to** make testing easier 
**I want** the gem to be easily installable from Github
**But** that is not the case if it enforces _semver_ because of [Bundler-Rubygems version numbering handling limitations](https://github.com/rubygems/rubygems/issues/724#issuecomment-29540109) 

The orignin of the issue is that while migrating to [Bundler-friendly version numbers](http://rubygems.org/gems/bundler/versions)  I didn't notice `1.0.0.pre.beta.4` would result to be greater than `1.0.0.beta.5`.