Add new autocomplete standard to docs & examples

This adds the new autocomplete attribute to Bootstrap.

Supported in Chrome stable, see:
http://blog.chromium.org/2012/11/a-web-developers-guide-to-latest-chrome.html

and

http://www.whatwg.org/specs/web-apps/current-work/multipage/association-of-controls-and-forms.html#autofilling-form-controls:-the-autocomplete-attribute


Since many sites are copying the Bootstrap examples & templates verbatim, it's seems like a good idea to encourage the standards, though totally understood if you don't think this fits in the project.