typo fix in bootstrap, vendors validation messages & validation that vendors/autoload.php exists

gulliver/system/class.bootstrap.php

@@ -3090,6 +3090,14 @@ class Bootstrap
             }
         } 
 
+        if (! file_exists(PATH_TRUNK . 'vendor' . PATH_SEP . "autoload.php")) {
+            throw new Exception(
+                "ERROR: Problems with Verdors!" . PHP_EOL .
+                    "Please execute the following command to repare vendors:" .PHP_EOL.PHP_EOL.
+                    "$>php composer.phar update"
+            );
+        }
+
         require_once PATH_TRUNK . 'vendor' . PATH_SEP . "autoload.php";
     }