Relocate SERVICE_TIMEOUT to stackrc

cinder_driver_cert.sh restarts volume services
and needs the SERVICE_TIMEOUT variable set, but
that was being declared in stack.sh.

Rather than create another duplicate variable in
the cert script, just move the SERVICE_TIMEOUT
variable to stackrc so it can be shared like other
common variables.

Change-Id: I650697df015fed8f400101a13b6165ac39626877
Closes-Bug: 1350221
diff --git a/stackrc b/stackrc
index 936eb9c..ac6efdd 100644
--- a/stackrc
+++ b/stackrc
@@ -516,6 +516,11 @@
 # (the default number of workers for many services is the number of CPUs)
 # API_WORKERS=4
 
+# Service startup timeout
+SERVICE_TIMEOUT=${SERVICE_TIMEOUT:-60}
+
+# Following entries need to be last items in file
+
 # Local variables:
 # mode: shell-script
 # End: