adds bower metadata file

Hiya,

Just a small addition: a `bower.json` file to allow registration of bindr with [Bower](http://bower.io/).
Should you accept the PR, then you can register your package with
`bower register bindr git://github.com/jcreamer898/bindr`

Oddly, even though you _have_ to provide a version number in `bower.json` this version number is ignored and Bower will only look at the tags created in the repo. So, if you register bindr with Bower, you _have_ to create a `v0.0.1` tag and push it to GH.

I excluded all directories except `dist`  from bower installation, but if you'd rather include the `docs` directory for instance, you'll need to remove that entry from `"ignore"`