Pulseaudio: fix non-working decrease_volume()
Pulseaudio: fix non-working decrease_volume()

Also change switch_mute() and increase_volume() to look similar to
decrease_volume()

enkore/i3pystatus,Arvedui/i3pystatus,fmarchenko/i3pystatus,facetoe/i3pystatus,Arvedui/i3pystatus,facetoe/i3pystatus,drwahl/i3pystatus,ncoop/i3pystatus,teto/i3pystatus,yang-ling/i3pystatus,enkore/i3pystatus,schroeji/i3pystatus,yang-ling/i3pystatus,m45t3r/i3pystatus,m45t3r/i3pystatus,richese/i3pystatus,teto/i3pystatus,ncoop/i3pystatus,fmarchenko/i3pystatus,drwahl/i3pystatus,schroeji/i3pystatus,richese/i3pystatus