Config graceful_shutdown_timeout option for services

To avoid hanging services during gracefull shutdown option
graceful_shutdown_timeout should be configured.

Closes-Bug: #1446583

Change-Id: I2b7f0df831d65c55ae8cae241478f49c9641d99f
diff --git a/stackrc b/stackrc
index 819aa01..1a95e2b 100644
--- a/stackrc
+++ b/stackrc
@@ -669,6 +669,9 @@
 # Service startup timeout
 SERVICE_TIMEOUT=${SERVICE_TIMEOUT:-60}
 
+# Service graceful shutdown timeout
+SERVICE_GRACEFUL_SHUTDOWN_TIMEOUT=${SERVICE_GRACEFUL_SHUTDOWN_TIMEOUT:-5}
+
 # Support alternative yum -- in future Fedora 'dnf' will become the
 # only supported installer, but for now 'yum' and 'dnf' are both
 # available in parallel with compatible CLIs.  Allow manual switching