Using pulseaudio by default

[Matthias Clasen]

Ok, we are getting close to test2, and we need to make a decision about 
this soon.

Here is a list of outstanding issues that we need to address for using
pulseaudio in F7:

- pulseaudio needs to work with suspend/resume (228205, has a patch)
- pulseaudio should work with fast user switching (228287)
- gstreamer-plugins-pulse needs to be in the default install
- gstreamer must be configured to should be configured to use the pulse 
plugin
- alsa-plugins-pulse needs to be in the distribution (222248)
- alsa needs to be configured to use the pulse plugin
- pulseaudio needs to be started at login, probably via an autostart file

Some of these changes affects more than the default desktop. If gstreamer
and alsa are configured to use pulseaudio, users won't here anything
unless pulseaudio is running, so kde and xfce will have to be prepared 
for this
too.