RFR: JDK-8226193: BundleNameTest and BundleIdentifierTest fails if run without network connection

[Alexander Matveev]

Please review the jpackage fix for bug [1] at [2].

This is a fix for the JDK-8200758-branch branch of the open sandbox 
repository (jpackage).

- Fixed by disabling loading external DTD files.

[1] https://bugs.openjdk.java.net/browse/JDK-8226193
[2] http://cr.openjdk.java.net/~almatvee/8226193/webrev.00

Thanks,
Alexander