user gomail and new activate account email tpl

- #1496: fallback plain text
- #1002: add date header
- #913: fix encoding of header

public/less/_form.less

@@ -46,6 +46,7 @@
 	}
 }
 
+.user.activate,
 .signin,
 .signup {
 	@input-padding: 200px!important;