New variable to control how long we let a batch job be idle before swapping.

This is primarily for the "queue an interactive job" form of batching,
but applies to all batch jobs at the moment.

sql/sitevars-create.sql

@@ -18,4 +18,5 @@ INSERT INTO sitevariables VALUES ('idle/cc_grp_ldrs',NULL,'3','Start CC\'ing gro
 INSERT INTO sitevariables VALUES ('batch/retry_wait',NULL,'900','Number of seconds to wait before retrying a failed batch experiment.');
 INSERT INTO sitevariables VALUES ('swap/idleswap_warn',NULL,'30','Number of minutes before an Idle-Swap to send a warning message. Set to 0 for no warning.');
 INSERT INTO sitevariables VALUES ('swap/autoswap_warn',NULL,'60','Number of minutes before an Auto-Swap to send a warning message. Set to 0 for no warning.');
+INSERT INTO sitevariables VALUES ('idle/batch_threshold',NULL,'30','Number of minutes of inactivity for a batch node/expt to be considered idle.');