Add dynamic version badge with link to npm package to the readme

Author: Simon Planinschek

readme.md

@@ -1,6 +1,8 @@
 Pagination
 ==========
 
+[![npm version](https://badge.fury.io/js/%40aboutbits%2Fpagination.svg)](https://badge.fury.io/js/%40aboutbits%2Fpagination)
+
 This pagacke includes a pagination calculation, where you can simply pass some basic information to the calcualtion function, and in return you receive an object with all relevant pagination information.
 
 ## Table of content