Chaser

I revisited the PR I submitted before now if you want any of my changes. I changed the tested process to use [Harp](http://harpjs.com), but I wouldn’t really expect you to want this whole pull request since you just re-did that stuff!

I’ve also kinda broken this out into its own thing I’ll probably be adding more to, called [Chasers](http://github.com/kennethormandy/chasers), so this is just all the updates from that. I realised afterwards that Omega Reset isn’t explicitly licensed, so hopefully that’s okay with you that I’m using it? Would you be open to releasing this mixin under MIT or similar? I made sure to keep all the Git history and links in place, but if you have any issue with it, just let me know and I can make changes. Thanks!