Update Bower configuration file and components directory

At present, running the development steps in the [README](README.markdown) results in failing Jasmine tests. This PR updates [Bower](http://bower.io/) configuration to fix this. The changes included are:

* Move `component.json` to `bower.json` as this has been the default configuration file since [Bower 0.9.0] (https://github.com/bower/bower/blob/master/CHANGELOG.md#090---2013-04-25)
* Update `grunt.js` and `.gitignore` to reference the new default Bower installation directory, which has been `bower_components` rather than just `components` since [Bower 0.10.0](https://github.com/bower/bower/blob/master/CHANGELOG.md#0100---2013-07-02)

This now means that the development steps execute without warnings and the Jasmine spec runs successfully.