Allow apache user alsa access

Vagrantfile

@@ -39,6 +39,8 @@ Vagrant.configure("2") do |config|
      rm ${alsa_deb}
      sudo DEBIAN_FRONTEND=noninteractive apt-get -y -m --force-yes install  alsa
      sudo usermod -a -G audio vagrant
+     # liquidsoap runs as apache
+     sudo usermod -a -G audio www-data
   SHELL
   config.vm.provision "shell", inline: "cd /vagrant; ./install -fIiapv --web-port=9080"
   config.vm.provision "shell", path: "docs/scripts/install.sh"