Updated to support turbolinks for rails 4 with graceful fallback

This is replacing my previous pull request and restoring Readme.md / gemspec definitions. They were changed temporarily to get a gem out in the interim until this patch got out into the wild.

It allows for rails 4 turbolinks support, which is going to become standard. It also gracefully falls back and has no affect on sites that do not use turbolinks. It does require changing the twitter bootstrap source files themselves slightly. I will see about submitting these patches to twitter bootstrap repository itself in the future.

Thanks,
David