Updates for bluetooth tethering support.

Full support only in KDE SC 4.7.0 because Plasma NM needs Solid 4.7.0 to
detect bluetooth network interfaces. In the mean time Plasma NM will treat
bluetooth network interfaces as gsm network interfaces. I still need to
implement bluetooth tethering for Cdma phones and Gsm/Cdma) Panu.

Without Solid 4.7.0 Plasma NM will not list the bluetooth interface nor
the bluetooth connection, so the only way to connect is setting the
bluetooth connection to autoconnect. There will be no notifications from
knotify either without Solid 4.7.0 and of course interface details tab
will not work because the interface is not listed.

BUG: 203584
CCBUG: 261191
FIXED-IN: 4.7.0