bug 985905: multi_host flag cunfusing settings

switch to using trueorfalse for parsing MULTI_HOST values.

Change-Id: I289563e0cd05cda014198cf21b3c88897aba5d4f
diff --git a/stack.sh b/stack.sh
index 71c5ffc..f657fe3 100755
--- a/stack.sh
+++ b/stack.sh
@@ -340,7 +340,7 @@
 # **MULTI_HOST** is a mode where each compute node runs its own network node.  This
 # allows network operations and routing for a VM to occur on the server that is
 # running the VM - removing a SPOF and bandwidth bottleneck.
-MULTI_HOST=${MULTI_HOST:-False}
+MULTI_HOST=`trueorfalse False $MULTI_HOST`
 
 # If you are using FlatDHCP on multiple hosts, set the ``FLAT_INTERFACE``
 # variable but make sure that the interface doesn't already have an