Volumes in Settings/Sound is slow to start

There is a delay after pressing volume menu item
there is a delay until the Volume popup is shown.

The reason for this is that the initialization of
the different seekbars is slow and run in the main
thread. More specifically the call to get the
ringtone from the RingtoneManager is causing this
delay.

Moving the call to the ringtone manager to the
handler thread used to play ringtones to make
the launch of the volume dialog a bit snappier.

Change-Id: I76da0226592468debd542d67164b37b2b59897c7