Add constructor entry 'tb_min_version'.

This is a requirement introduced recently by the validation script.

sendtoafriend.php

@@ -49,6 +49,7 @@ function __construct($dontTranslate = false)
 			$this->description = $this->l('Allows customers to send a product link to a friend.');
  		}
 		$this->tb_versions_compliancy = '> 1.0.0';
+		$this->tb_min_version = '1.0.0';
 		$this->ps_versions_compliancy = array('min' => '1.6', 'max' => '1.6.99.99');
 	}