match devstack-gate format

support millisecond resolution and the | separator for ts vs.
content.

everything else in openstack is running at millisecond resolution,
and some times it's actually useful to see that when debugging
gate failures.

Change-Id: I2227ab0b4965cd1a24b579bdf2ba8c1f9a432f70
diff --git a/stack.sh b/stack.sh
index c153132..eaccc76 100755
--- a/stack.sh
+++ b/stack.sh
@@ -530,9 +530,9 @@
         # Redirect stdout/stderr to tee to write the log file
         exec 1> >( awk '
                 {
-                    cmd ="date +\"%Y-%m-%d %H:%M:%S \""
+                    cmd ="date +\"%Y-%m-%d %H:%M:%S.%3N | \""
                     cmd | getline now
-                    close("date +\"%Y-%m-%d %H:%M:%S \"")
+                    close("date +\"%Y-%m-%d %H:%M:%S.%3N | \"")
                     sub(/^/, now)
                     print
                     fflush()