Set up the keyboard volume keys and the volume indicator to behave a
little more dynamically based on whether the default sound device
has a Master interface or not. Also finally got the new gradient
system from awesome 3.5 working. Credit goes to psychon on the awesome
wiki for the initial push and to tdy for showing me that the wiki
is missing a } in the example. (I have also fixed that on the wiki,
so it should now be correct)