add timing infrastructure to devstack

this adds a timing infrastructure to devstack to account for time
taken up by set of operations. The first instance of this is
accounting the time taken up by doing apt_get calls.

Change-Id: I855ffe9c7a75e9943106af0f70cf715c34ae25c5
diff --git a/stack.sh b/stack.sh
index b65c558..1976dff 100755
--- a/stack.sh
+++ b/stack.sh
@@ -1366,6 +1366,8 @@
     exec 1>&3
 fi
 
+# Dump out the time totals
+time_totals
 
 # Using the cloud
 # ===============