Improve waiting for vpn process to end

cvpn

@@ -433,9 +433,8 @@ elif [[ $cmd == "off" ]]; then
             thepid=$(cat ${pidfile[$x]})
             if [[ -n $thepid ]]; then
                 sudo kill $thepid
-                sleep 2 # give it some time
-                res=$(ps -p $thepid 2>&1)
-                if [[ $? -ne 0 ]]; then
+                wait $thepid # wait for the process to end
+                if [[ $? -eq 0 ]]; then
                     rm -f "${pidfile[$x]}"
                     rv=0
                 else