feat(pagination): add first/last link & constant congif options.

 * Options for text of first, previous, next & last links.
 * Option "boundary-links" whether to display "first" & "last" link
   (default: false)
 * Option "direction-links" whether to display "previous" & "next" link
   (default: true)
 * Added tests!!!
 * Fix demo to show all possible configuration options