fixed missing add-apt-repository command when ubuntu is the server one

dev/setup-salt.sh

@@ -1,5 +1,7 @@
 #!/bin/sh
-sudo apt-add-repository ppa:saltstack/salt -y
+sudo apt-get update -y
+sudo apt-get install python-software-properties pkg-config software-properties-common -y
+sudo add-apt-repository ppa:saltstack/salt -y
 sudo apt-get update -y
 sudo apt-get install salt-master -y
 sudo apt-get install salt-minion -y