Further fix of email receipt regression (#475)

application/views/sales/receipt.php

@@ -12,7 +12,7 @@ if (isset($error_message))
 <script type='text/javascript'>
 $(document).ready(function()
 {
-	var send_mail = function()
+	var send_email = function()
 	{
 		$.get('<?php echo site_url() . "/sales/send_receipt/" . $sale_id_num; ?>',
 			function(response)
@@ -22,7 +22,7 @@ $(document).ready(function()
 		);
 	};
 
-	$("#show_email_button").click(send_mail);
+	$("#show_email_button").click(send_email);
 
 	<?php if(!empty($email_receipt)): ?>
 		send_email();