Process Bluez5 URLs during SDP scan

Bluez5 advertises the following SDP attributes
- QBluetoothServiceInfo::DocumentationUrl
- QBluetoothServiceInfo::ClientExecutableUrl
- QBluetoothServiceInfo::IconUrl

They come as <url> xml tag but otherwise follow the <text> syntax.
So far this type of xml tag was unknown, a warning was printed
and the service info didn't contain the relevant info.

Although Bluez5 seems to be the first to advertise this attribute,
Bluez4 has to be able to deal with it too. Hence this patch goes
to Qt 5.3/stable.

Change-Id: I216fdaee23c75b1ed86702086be2d95a0efe109e
Reviewed-by: Aaron McCarthy <mccarthy.aaron@gmail.com>
Bluez4: Ensure QBluetoothLocalDevice becomes invalid if adapter disappears

The DBus object disappears when the dongle is removed. Once a
QBluetoothLocalDevice instance is invalid it remains invalid.
The patch further ensures that an invalid instance does not
initiate pairing activitiy.

Last but not least this patch fixes a memory leak in case
a DBus error occurs during the adapter initialization.

Task-number: QTBUG-38399
Change-Id: I2e13e393060c77fab5f79d5451dd6fe9a2a6e3bb
Reviewed-by: Aaron McCarthy <mccarthy.aaron@gmail.com>