[commhistory-daemon] Handle MMS send/delivery state changes
[commhistory-daemon] Add MmsHandler::sendMessage dbus methods

The sendMessage method handles recording outgoing MMS events for
commhistory, storing message part files, and sending the actual MMS
request to the engine.

sendMessageFromEvent can be used to send a message to the MMS engine
based on an existing event.
Merge pull request #43 from special/mms-send

[commhistory-daemon] Add MMS send state handling and helpers