add pagination for Twitter Bootstrap 3

Hi Akira.

I've made some additions to your great library.
I've checked other similar pull requests before creating mine.
I think this one is doing the smallest changes in your library
and at the same time bringing correctness and precision.

Have a look at the changes please:
Add separately slightly different pagination for Bootstrap 3

   - it has not 'div' wrapper around 'ul'
   - it assigns 'pagination' class to 'ul'

Change directory and correct description for Bootstrap 2

Thanks for your wonderful work.
Pavel