Allow to specify pulseaudio server instead of using default one.

Add "server" entry to pa config section, allowing to connect to a remote or a local system
pulseaudio instance instead of letting pulseaudio choose.

scripts/shairport-sync.conf

@@ -118,6 +118,7 @@ sndio =
 // --with-pa
 pa =
 {
+//	server = "host"; // Set this to override the default pulseaudio server that should be used.
 //	application_name = "Shairport Sync"; //Set this to the name that should appear in the Sounds "Applications" tab when Shairport Sync is active.
 };