refactor ping_check

Encapsulate all the neutron specific things you have to do ping a
neutron guest into a separate script. Refactor the main ping_check so
all logic is contained within it.

Change-Id: Ic79d8e3a2473b978551a5635a11dba07e1020bb2
diff --git a/exercises/volumes.sh b/exercises/volumes.sh
index 3ac2016..f95c81f 100755
--- a/exercises/volumes.sh
+++ b/exercises/volumes.sh
@@ -143,7 +143,7 @@
 die_if_not_set $LINENO IP "Failure retrieving IP address"
 
 # Private IPs can be pinged in single node deployments
-ping_check "$PRIVATE_NETWORK_NAME" $IP $BOOT_TIMEOUT
+ping_check $IP $BOOT_TIMEOUT "$PRIVATE_NETWORK_NAME"
 
 # Volumes
 # -------