Fake "invalid" hostnames used in tests are sometimes valid

Some of the ZooKeeper tests use "fake" hostnames to trigger host resolution failures. The problem with this is that it uses valid hostnames which are sometimes configured in VMs.

At the moment I am unable to build cleanly because I get test failures on the two test methods that do this. The tests work equally well if syntactically invalid hostnames are used, and the test cases become more portable at the same time.

The affected test cases are:

org.apache.zookeeper.test.StaticHostProviderTest.testTwoInvalidHostAddresses and org.apache.zookeeper.test.StaticHostProviderTest.testOneInvalidHostAddresses

See GitHub pull request https://github.com/apache/zookeeper/pull/48 for a proposed fix