Improved logic for handling permissions on API routes.

Still only partially implemented, however this method will allow the
inclusion of data that is granted with servers (such as viewing more
about the node, node location, allocations, etc) while still limiting
someone from doing `?include=node.servers` and listing all servers when
they don’t have list-servers as a permission.

app/Models/APIKey.php

@@ -28,6 +28,13 @@ use Illuminate\Database\Eloquent\Model;
 
 class APIKey extends Model
 {
+    /**
+     * Public key defined length used in verification methods.
+     *
+     * @var int
+     */
+    const PUBLIC_KEY_LEN = 16;
+
     /**
      * The table associated with the model.
      *