Provide support for jQuery UI Datepicker 2.0

Adding MR for this code.

For those interesting to test it you need to change your composer.json repositories section like this:

    "repositories": [
      {
          "type": "git",
          "url": "https://git.drupalcode.org/issue/daterangepicker-3383923.git"
      },
      {
          "type": "composer",
          "url": "https://packages.drupal.org/8",
          "exclude": ["drupal/daterangepicker"]
      }
    ],

And then launch composer require drupal/daterangepicker:dev-3383923-jquery-ui-datepicker-2.0

Cleaning up my old issues. I've merged this to 1.0.x branch.

Automatically closed - issue fixed for 2 weeks with no activity.