- core: ignore some failures on disconnect (rh #578280)
    - core: add support for platform serial devices
    - gsm: better Blackberry DUN support
    - gsm: periodically poll access technology
    - cdma: prevent crash on modem removal (rh #571921)
    - mbm: add support for Sony Ericsson MD400, Dell 5541, and Dell 5542 modems
    - novatel: better signal strength reporting on CDMA cards
    - novatel: add access technology and mode preference support on GSM cards
    - zte: fix mode preference retrieval
    - longcheer: add support for Zoom modems (4595, 4596, etc)
    - longcheer: add access technology and mode preference support