bower file

As this a mostly front end tool it would be great to add support for bower.io, meaning users can install bio-js to their project with:
`bower install biojs/biojs --save`
(if the pull request is accepted and biojs is registered on the bower servers (much like npm's system) it can be shortened to just:
`bower install biojs --save`

The trend in component management has pushed NPM into use for back end (server side) components and BOWER for front end (client side).