See also PR #917
This patch does the following:
* Moves the docstring for the deprecated "protocol" alias to be
below the new, recommended "scheme" attribute.
* Changes the type of "port" to an int to be consistent with the
parse_host() utility function.
* Expand the "port" docstring.
* Add a docstring for "netloc".
* Implement "uri" in terms of "netloc".
* Handle default port in the try block, since that it is not
necessary to do so in the case that SERVER_PORT is used.
* In the tests, inherit from TestCase instead of the deprecated
TestBase class.
* DRY up the tests.
* Test the new attributes with both the HTTP/1.0 and HTTP/1.1
protocols.