Allowed comma-delimited list in smtp $to var to be consistent with st…

…andard mail delivery. Fixes cakephp#1353

cake/libs/controller/components/email.php

@@ -861,7 +861,7 @@ function _smtp() {
 		}
 
 		if (!is_array($this->to)) {
-			$tos = array($this->to);
+			$tos = array_map('trim', explode(',', $this->to));
 		} else {
 			$tos = $this->to;
 		}