Rename lib/neutron to lib/neutron-legacy

Preparing to refactor lib/neutron to support Neutron as the default
network config.  lib/neutron will be renamed internally and refined
to support a couple of specific configurations.

Change-Id: I0d3773d14c4c636a4b915734784e7241f4d15474
diff --git a/exercises/volumes.sh b/exercises/volumes.sh
index 504fba1..3ac2016 100755
--- a/exercises/volumes.sh
+++ b/exercises/volumes.sh
@@ -32,7 +32,7 @@
 
 # Import project functions
 source $TOP_DIR/lib/cinder
-source $TOP_DIR/lib/neutron
+source $TOP_DIR/lib/neutron-legacy
 
 # Import exercise configuration
 source $TOP_DIR/exerciserc