Added bower.json

Tested install locally including running with [generator-angular-fullstack](https://github.com/DaftMonk/generator-angular-fullstack) so the file is added to `bower_components` scripts in `index.html` and it works (_adds minified version_).

Did not publish to bower registry and this version has `private` set to `true` per your discretion.

To test local install:
1. Clone repo to local
2. `npm install` to get Grunt for build
3. `grunt build` to generate `build` folder with both full and minified files
4. Navigate to the folder with desired project
5. run `bower install ng-socket-io ~/path/to/ng-socket-io/location/bower.json`