Ability to provide API Key via wp-config.php

[bhubbard]

It would be nice to provide an option to set API Key via the wp-config.php file. Similar to setting the WordPress url, the settings page would display the field but gray it out so it can only be changed via the wp-config.php file.

define('IDXBROKER_API_KEY', 'your_api_key');

define('IDXBROKER_PARTNER_API_KEY', 'your_partner_api_key');