Refactoring and improvements

@loudenvier I finally got some time to convert all the language files to .json. This pull requests contains the following (big) changes:
1. All language files are converted to .json
2. Gulp is added for building tasks. Both the .js files and demo files are automatically generated (see README.md)
3. Added `bower.json` file, so the repository can be distributed via Bower.
4. Updated README to reflect the above described changes.