Add 'version' parameter and support for Bootstrap 3

Bootstrap 3 changed the structure of the 'pagination' component, which
required some small changes. The plug-in still defaults to Bootstrap 2 for
backwards compatibility.
Add script to generate HTML pages for manual inspection

Uses .css files from the Bootstrap CDN and generates various pagers in a
HTML document for visual checks.
Add 'size' parameter to support sizing of the pagination component

Newer Bootstrap versions support an optional CSS class which influences
the size of the pagination component.
Update Changes file
Add basic tests for new 'size' parameter