refactor(auth): change contributor's role logic to have it included in the users_podcasts table

- update myth-auth and codeigniter to latest develop changes
- improve permission check: remove all
dynamic permissions per podcast and overwrite myth-auth services and permission filter
- remove
unnecessary code because of myth-auth upgrade
- refactor some controller code for better clarity
-
add remaining seeders in docs

closes #19, #20

app/Entities/User.php

@@ -0,0 +1,42 @@
+<?php namespace App\Entities;
+
+use App\Models\PodcastModel;
+
+class User extends \Myth\Auth\Entities\User
+{
+    /**
+     * Per-user podcasts
+     * @var \App\Entities\Podcast[]
+     */
+    protected $podcasts = [];
+
+    /**
+     * Array of field names and the type of value to cast them as
+     * when they are accessed.
+     */
+    protected $casts = [
+        'active' => 'boolean',
+        'force_pass_reset' => 'boolean',
+        'podcast_role' => '?string',
+    ];
+
+    /**
+     * Returns the podcasts the user is contributing to
+     *
+     * @return \App\Entities\Podcast[]
+     */
+    public function getPodcasts()
+    {
+        if (empty($this->id)) {
+            throw new \RuntimeException(
+                'Users must be created before getting podcasts.'
+            );
+        }
+
+        if (empty($this->podcasts)) {
+            $this->podcasts = (new PodcastModel())->getUserPodcasts($this->id);
+        }
+
+        return $this->podcasts;
+    }
+}