bower manifest

Hi, I recently started using [Bower](http://bower.io/). Would you be willing to register this project as a Bower package? If I'm not mistaken, the following steps are required:

1. node & npm installed: `brew install node` on OS X using Homebrew
2. npm executables on your PATH: `export PATH=/usr/local/share/npm/bin:$PATH && hash -r`
3. bower installed: `npm install -g bower`
4. and finally, you can register the project in the bower package registry: `bower register srcset-polyfill https://github.com/JimBobSquarePants/srcset-polyfill.git`

that should be it.