Change users_cms variable to an array

Currently we have:

        users_cms: wordpress
        wordpress_dbname: wordpress
        wordpress_dbname: wp_live
        wordpress_url: https://www.wp.wsh.webarchitects.org.uk
        wordpress_title: "WordPress Blog"
        wordpress_admin_user: chris
        wordpress_admin_email: chris@webarch.coop

Something like this would be better to allow multiple CMS' to be installed per VirtualHost:

        users_cms:
          - name: wordpress
            title: WordPress Blog
            url: https://example.org/blog
            path: /blog
            db_name: foo
            db_prefix: blog_
            admin_user: chris
            admin_email: chris@webarch.coop
          - name: flarum
            path: /forum
            db: foo
            db_prefix: forum_