Upgrade to guard ver 2

Hello :)

While working with some Guard plugins, I noticed faulty behaviour when editing files with VIm (most notably running multiple times) and I took it upon myself to:
- fix VIm behaviour
- upgrade said Gem to Guard 2.0 Plugins

I hope you find this patch useful enough to accept it.

If you want to, I'd be willing to clone the zeus functionality for spring in another feature branch.

Thanks for your time
-killphi