Initial integration of the new MM iface in NM (v2)

[Aleksander Morgado <aleksander lanedo com>]

The following patches introduce the new ModemManager1 interface support.

The logic to watch for modem additions and removals is now done in the
'NMModemManager' object both for the old and the new interfaces.

[PATCH 1/8] build: new `--with-modem-manager-1' to check for new
[PATCH 2/8] modem-manager: rename old interface symbols
[PATCH 3/8] modem-manager: new `NMModemBroadband'
[PATCH 4/8] modem-manager,manager: integrate the new `ModemManager1'
[PATCH 5/8] modem-manager,manager: avoid calling
[PATCH 6/8] device-bt,device-modem: listen for data port changes in
[PATCH 7/8] modem-manager: don't report the data interface along
[PATCH 8/8] device-bt: watch both old and new ModemManager interface