[ticket/12613] Improved pagination styling & page-jump

https://tracker.phpbb.com/browse/PHPBB3-12613
http://area51.phpbb.com/phpBB/viewtopic.php?f=108&t=45433

![pagi](https://cloud.githubusercontent.com/assets/3015760/3124023/e12655da-e778-11e3-8b7b-a1c8b4388e2c.png)

Depends on https://github.com/phpbb/phpbb/pull/2517

Tested:
- [x] IE8
- [x] IE9
- [x] IE10
- [x] IE11
- [X] FF29
- [X] Chrome 35
- [x] Safari 5.1 (Windows)
- [X] Safari 7 (Mac)
- [x] Opera 21
- [X] Responsive
Move `background-repeat` here instead of setting it on each one individually.