Inform user when a file will not be overwritten due to age

We had a build failing due to the <overwrite /> tag not being set in the maven-resources-plugin. It took me a bit to figure out the issue because the debug output kept reporting that it was copying over the file when in fact it wasn't. It would have helped out a bit if the plugin (via this dependency) had reported that it was, in fact, not copying over the file.

See attached patch for suggested change (and accompany JUnit test). Some caveats:

• I'm afraid I don't know where to get the Eclipse code style used for these projects, so, if the format of the code is objectionable, let me know where to get the Eclipse code style and I'll re-submit the patch with the applied stylings.
• The code should be compatible with Java 1.4, but I wasn't able to fully verify because part of the build brought in a Java 5 dependency and the build wouldn't pass without that. I don't imagine its non-compliance with Java 1.4 is too terrible, given that nothing after Maven 2.0.11 supports it, but it seemed worth noting just in case I'm wrong.