Remove validation on Block Title field

As mentioned in #95

code/dataobjects/Block.php

@@ -202,20 +202,6 @@ public function getCMSFields()
         return $fields;
     }
 
-    /**
-     * @return ValidationResult
-     */
-    public function validate()
-    {
-        $result = parent::validate();
-
-        if (!$this->Title) {
-            $result->error(_t('Block.TitleRequired', 'Block Title is required'));
-        }
-
-        return $result;
-    }
-
     /**
      * Renders this block with appropriate templates
      * looks for templates that match BlockClassName_AreaName