Add a Contributor custom post type (#42)

Contributors associated with pledges have a state: they can be confirmed or unconfirmed. They also have some important meta data, namely when they were confirmed. Thus, managing contributor data for pledges is more robust if we treat them as their own post type instead of as a multidimensional array of post meta data.

This also reorganizes some of the functions related to pledges so that things are more consistent between the pledge CPT and the contributior CPT.

Fixes #11

plugins/wporg-5ftf/index.php

@@ -23,6 +23,7 @@ add_action( 'plugins_loaded', __NAMESPACE__ . '\load' );
  *
  */
 function load() {
+	require_once get_includes_path() . 'contributor.php';
 	require_once get_includes_path() . 'pledge.php';
 	require_once get_includes_path() . 'pledge-meta.php';
 	require_once get_includes_path() . 'pledge-form.php';