Fixing DefaultResourceDao.findNodeSourceDirectories()

There was an invalid filter used on that method that was preventing
listing all the node resources properly when storeByForeignSource is
enabled.

FindTopLevelResourcesTest has been updated to validate that it should
work as expected.

Solution also tested on running environment.
Displaying storeByForeignSource on /admin/sysconfig.jsp
Merge remote-tracking branch 'origin/1.12'

Conflicts:
	opennms-dao/src/main/java/org/opennms/netmgt/dao/support/DefaultResourceDao.java
	opennms-dao/src/main/java/org/opennms/netmgt/dao/support/RrdFileConstants.java