Crank up dbench, now that everything seems to be quite stable under load.

We now do 1, 10, 50, and 100 client runs each night.
Make sure the path back to the scripts directory is available in the
environment for scripts to get at if need be.

run.dbench50

@@ -0,0 +1,8 @@
+#!/bin/sh
+# 
+# Does a dbench run with 50 clients
+# 
+DBENCH_CLIENTS=50
+export DBENCH_CLIENTS
+
+exec $here/common.dbench