Polymer implementation of dragula D&D handling

Example:

    <polymer-dragula>
        <div class="row-holder">
            <div class="column">
                <p>item-1</p>
            </div>
            <div class="column">
                <p>item-2</p>
            </div>
            <div class="column">
                <p>item-3</p>
            </div>
            <div class="column">
                <p>item-4</p>
            </div>
            <div class="column">
                <p>item-5</p>
            </div>
        </div>
    </polymer-dragula>

First, make sure you have the Polymer CLI installed. Then run polymer serve to serve your application locally.

$ polymer serve

$ polymer build

This will create a build/ folder with bundled/ and unbundled/ sub-folders containing a bundled (Vulcanized) and unbundled builds, both run through HTML, CSS, and JS optimizers.

You can serve the built versions by giving polymer serve a folder to serve from:

$ polymer serve build/bundled

$ polymer test

Your application is already set up to be tested via web-component-tester. Run polymer test to run your application's test suite locally.