grunt-bump (proposal to resolve #5047)

I've added a `Gruntfile.js` that could handle the versioning on Github, npm and Bower. See the grunt-bump [usage examples](https://github.com/vojtajina/grunt-bump#usage-examples) on how to make use of this.

I also created a basic `bower.json` resembling the existing `package.json`. Is there a specific reason why the version in `package.json` lags behind the git tag?