Deal with the user-entered g2 embed.php path a little more sanely so that if the user enters the path to G2 itself, we find the embed.php path from there.

modules/g2_import/helpers/g2_import.php

@@ -52,6 +52,10 @@ class g2_import_Core {
    * Initialize the embedded Gallery2 instance.  Call this before any other Gallery2 calls.
    */
   static function init_embed($embed_path) {
+    if (!is_file($embed_path)) {
+      return false;
+    }
+
     require($embed_path);
     if (!class_exists("GalleryEmbed")) {
       return false;