Built-in support for bullets and arrows

Sorry for the multiple contributors, i had a small problem with my git username. So i kept pushing to test if it works :)

I have added bullets to the swipe library so now users can have bullets indicating the progress of their slides and also built in support for arrows for people that don't want to deal with the API and just with CSS/HTML.

I have updated the demo file so you can see what i have done. I have always loved and used swipe and i always had to have JS code for bullets and for arrow buttons.

About me: I work as a senior web developer for Cheil UK (big agency - biggest Samsung partners in the UK) - http://uk.linkedin.com/in/alexandrub

I will continue contributing to Swipe because i just love it and i hope you will accept my pull request.

Let me know if you have any questions.

Thank you.

Alex