SIM objects will be listed as independent objects in the DBus API, and the 'Sim'
property in a given modem object will specify which SIM object is in use.
Main changes are cleaning up the API and allowing for multi-mode
devices that support two or more of CDMA/EVDO, GSM/UMTS, and LTE
at the same time. This provides a starting discussion point for
the new MM 0.6 API.