Add tests

[atc0005]

Lots of tests. Or, just a few tests, but tests we should have.

In particular, XPath queries against a sample configuration file reflecting what I've found in each of the three LOCKSS networks I've tested this tool against.

In the example files, I should hard-code some IPs that should not be returned, and some that should. I should (for the sake of recognition), re-use the same sets across all three files as appropriate. This way, a "should never match" IP can be recognized by sight in the tests if needed.

There is room for tests across the board however, so at this point nearly anything would be useful.