CMS-26 CMS-29 Add auto slide directive

At the very beginning, we chose angular-flexslide as our carousel plugin for web-cms. However, angular-flexslider has dependency on JQuery which broke the login function in Tab-oo.

The latest version of Angular-carousel doesn't support auto slide function, a separate directive called 'rn-carousel-auto-slide' was added in this PR. Also a demo was also added to index.html.