Allow configuration management through settings.php

We deploy our codebase to multiple environments and would like to manage configuration in site specific settings files. The attached patch allows us to override the storage containers.

Features or strongarm exportability would be nice, but there are few hurdles. Chief among them is that the ID may be different on different machines. It's not for us, so this works fine.

This module allows you to specify container settings in your settings.php file in a format similar to the following:

/**
 * Storage API settings
 *
 * Key would be container ID as appears in storage API config. Note that this
 * only makes sense for a specific type of deployment with predictable IDs. This
 * use case happens to be one of them.
 */
$conf['storage_api_container_settings'] = array(
  '1' => array(
    'path'     => 'sites/local/files/somewhere',
    'base_url' => 'sites/local/files/somewhere',
  ),
  '2' => array(
    'access_key_id'        => 'ACCESSKEYHERE',
    'secret_access_key'    => 'SECRETKEYHERE',
    'bucket'               => 'mybucket',
    'cname'                => 1,
    'reduced_redundancy'   => 0,
    'cloudfront'           => 0,
    'cloudfront_streaming' => 0,
    'location'             => '',
    'url_lifetime'         => 3601,
  ),
);