Add container accessor

[deefour]

The AWS S3 adapter has a public getClient() method, allowing for access and use of the raw S3Client instance.

The Rackspace adapter doesn't have a similar accessor for the underlying OpenCloud container.

@frankdejonge described adding a Rackspace-only plugin to fetch a CDN URL for an object. This can't be done without access to the container.

Also related to #2, #3, and #6, here's a plugin providing a getUrl() method on the adapter.

<?php

namespace League\Flysystem\Rackspace\Plugin;

use Guzzle\Http\Url;
use League\Flysystem\Plugin\AbstractPlugin;
use League\Flysystem\NotSupportedException;
use OpenCloud\ObjectStore\Constants\UrlType;

class GetUrl extends AbstractPlugin
{
    /**
     * Get the method name.
     *
     * @return string
     */
    public function getMethod()
    {
        return 'getUrl';
    }

    /**
     * Get the Url object for a path.
     *
     * @param string $path     path to file
     * @param string   $urlType  OpenCloud URL type
     *
     * @return Url
     */
    public function handle($path, $urlType = UrlType::SSL)
    {
        $container = $this->filesystem->getAdapter()->getContainer();

        if ( ! $container->isCdnEnabled()) {
          throw new NotSupportedException(
            'The Rackspace container must be CDN-enabled to fetch a public URL for ' . $path
          );
        }

        return $container->getObject($path)->getPublicUrl($urlType);
    }
}

[frankdejonge]

@deefour merged an released as 1.0.2

[deefour]

@frankdejonge :beers:

[ShortlyMAB]

<3