Add tests of caps from the future that have non-ASCII characters in them (encoded...

Add tests of caps from the future that have non-ASCII characters in them (encoded as UTF-8). The changes to test_uri.py, test_client.py, and test_dirnode.py add tests of non-ASCII future caps in addition to the current tests. The changes to test_web.py just replace the tests of all-ASCII future caps with tests of non-ASCII future caps. We also change uses of failUnlessEqual to failUnlessReallyEqual, in order to catch cases where the type of a string is not as expected.