Bootstrap overrides: Increased specificity of pagination and pager's arr...

...ow SCSS selectors and disabled them in IE8...

* Prevents the arrows from appearing when rel attributes are set on numbered links that have the same destinations as the "Previous"/"Next" links.
* Arrows have been disabled in IE8 since it lacks support for :last-child (would look really strange if only :first-child arrows continued to be shown).