fix template_url shortcode return code error

[ghost]

The template_url shortcode does not check the possibility of strpos() returning false and produces a php error in the next line. The following patch fixes the problem.

--- html.php.orig   2014-06-08 13:30:14.000000000 +0300
+++ html.php    2014-06-08 13:31:42.469818131 +0300
@@ -466,8 +466,10 @@
        $content_str  = 'wp-content';

        $pos          = strpos($content_url, $content_str);
-       $template_url = substr($content_url, 0, $pos-1);
-       return $template_url;
+       if($pos!==false)
+           return substr($content_url, 0, $pos-1);
+       else
+           return $content_url;
    }
    add_shortcode('template_url', 'template_url_shortcode');
 }