Slave node should try to get lock in small intervals to check JDBC connectivity

In a JDBC master/slave configuration, the master node gets the lock in the database table ACTIVEMQ_LOCK and becomes active. The slave node tries to get the lock and waits indefinitely on the SQL query.
In case of a network device failure, the TCP connection to the DB server is abruptly removed, and no FIN nor RST is sent to the broker. This results into a slave node which never resumes from this network issue without manual restart of the broker.
The attached patch transforms the indefinite wait on the lock into a loop in small time intervals (defined by the "queryTimeout" variable). Also, it becomes possible to specify a TCP socket timeout at the JDBC driver level (for instance "oracle.jdbc.ReadTimeout" for Oracle) as an extra safety measure.
In the default case, the "queryTimeout=-1", which falls back to the indefinite wait.