Enable Bower installation of library

I've modified the Gruntfile and dependencies to be able to install the library through [Bower](http://bower.io/):

* Add the Bower JSON file that lists information about the app and dependencies
* Create clean and copy Grunt tasks to copy datamaps libraries to the root directory for bower install
* Add copy task to the build task

To publish the code to the bower registry, merge the pull request, install Bower with `npm install -g bower` and then run the following command to register:

    bower register datamaps markmarkoh/datamaps