Move range parsing to separate classes (Fixes #1)

This is my solution for #1. I hope you like the idea behind this.

* All parsers are derived from RangeParser class  
  Based on Olsen, Russ: Eloquent Ruby (2011) pp. 250-253  
  http://eloquentruby.com/
* I added `ReissueParser` with my first commit. You can move this class to your private application.