change notification sound and volume

```
What version of the product are you using? On what operating system?
0.1.7.2 Windows 8.1

Please provide any additional information below.

I was wondering if you can allow us to change the volume of the notifications
of mute and unmute. Right now these sounds are very basic and they are
extremely loud they hurt my ears.

I would turn them off but I would like to know when my mic is muted in game and
the notification boxes to not show up in game when playing BF4.

When I lower the volume for mic mute in the windows volume mixer it has no
affect on the volume of these sounds. I would lie to be able to add a custom
sound for mic mute and mic activate and to be able to control the volume of
these sounds on a application basis.

Love your work an ty SIR!

Justin

```

Original issue reported on code.google.com by `ciscoipt...@gmail.com` on 24 Jan 2014 at 11:30