Test update for Ruby 2.2 (not yet)

From Ruby 2.2 URI uses RFC3986 parser instead of traditional RFC2396
parser.  Maybe unintentionally, new parser successfully parses 'http://'
as a valid URI in contrast to the old parser raises InvalidURIError.

The test in httpclient is for checking URI exception handling so I just
changed the test data to 'http://あ' which causes InvalidURIError with
both parsers.