Add Composer support

[Composer](http://getcomposer.org) is a package manager for PHP. This allows jQuery-Timepicker-Addon to be downloaded by putting "trentrichardson/jquery-timepicker-addon" into your own composer.json file.
```json
{
  "require": {
    "trentrichardson/jquery-timepicker-addon": "~1"
  }
}
```
Please update the jqueryui dependency like you update it in component.json.

*Notice that I had to set the jqueryui dependency to 1.10.2, because the versions before do not exist for Composer. So start updating the jqueryui dependency when you require jqueryui > 1.10.2*