fixed wrong command name: add-apt-repository became apt-add-repository

dev/setup-salt.sh

@@ -1,5 +1,5 @@
 #!/bin/sh
-sudo add-apt-repository ppa:saltstack/salt -y
+sudo apt-add-repository ppa:saltstack/salt -y
 sudo apt-get update -y
 sudo apt-get install salt-master -y
 sudo apt-get install salt-minion -y