Do not delete an SMS if there is no text in it

If the sms contains data and not text (like for an MMS), chatty will delete the SMS. This isn't desirable, as if mmsd-tng isn't running, the SMS WAP is going to be deleted and the user will miss the message

The SMS is not deleted if the state of the SMS is MM_SMS_STATE_RECEIVED, instead of MM_SMS_STATE_RECEIVING.

This MR fixes both of those issues.