Update PHPMailer to version 5.2.8 and add Russian translation file

Update PHPMailer from version 5.2.7 to 5.2.8
- Better RFC adherence for timeouts, headers, encodings
- Much faster SMTP
- Return-path header is no longer set (it never should have been)
- HTML5 spec email validation...

Add Russian translation file (thanks to a-x-)