add bower.json file

per instructions on [http://bower.io/docs/creating-packages/](http://bower.io/docs/creating-packages/)
i ran `$ bower init` and created the file.

Once the pull request is accepted we can:
  1. add git tags for versionning
  2. register the package
  [http://bower.io/docs/creating-packages/#register](http://bower.io/docs/creating-packages/#register)
  3. Update README with installation instructions
  `$ bower install gapless5 --save`