DERBY-626 Re-work code to ensure that obtaining the enumeration of modules.properties files as well as opening them is in a priviledge block. Removes the requirement for read permission on derby.jar to be granted all the way up the stack when running with the security manager. Merge of 326727 from trunk
db/derby/code/branches/10.1/java/engine/org/apache/derby/impl/services/monitor/BaseMonitor.java