Bug 835148: Implement SmsEvent using event generator. r=smaug

--HG--
rename : dom/sms/interfaces/nsIDOMSmsEvent.idl => dom/sms/interfaces/nsIDOMMozSmsEvent.idl
rename : dom/sms/interfaces/nsIDOMSmsMessage.idl => dom/sms/interfaces/nsIDOMMozSmsMessage.idl