Fix for Missing trailing slash on inet_http_server redirects

[lukeweber]

Fixes #640 - get_server_url() strips the trailing "/", so it has to be added back on the redirect between the host and http args.

http.py

    def get_server_url(self):
        """ Functionality that medusa's http request doesn't have; set an
        attribute named 'server_url' on the request based on the Host: header
        """
        default_port={'http': '80', 'https': '443'}
        environ = self.cgi_environment()
        if (environ.get('HTTPS') in ('on', 'ON') or
            environ.get('SERVER_PORT_SECURE') == "1"):
            # XXX this will currently never be true
            protocol = 'https'
        else:
            protocol = 'http'

        if 'HTTP_HOST' in environ:
            host = environ['HTTP_HOST'].strip()
            hostname, port = urllib.splitport(host)
        else:
            hostname = environ['SERVER_NAME'].strip()
            port = environ['SERVER_PORT']

        if port is None or default_port[protocol] == port:
            host = hostname
        else:
            host = hostname + ':' + port
        server_url = '%s://%s' % (protocol, host)
        if server_url[-1:]=='/':
            server_url=server_url[:-1]
        return server_url

[mnaberez]

@rafis @lukeweber @calvin Could you guys please review this against #593?

That pull request is another attempt at better proxy support that also makes the URL more configurable. If #593 also fixes this issue maybe we should just merge that. I'm not using the web interface behind a proxy server so I appreciate your feedback.

[calvin]

#593 fixes this by introducing new base_path setting. Also it ensures the trailing / always exists. (https://github.com/Supervisor/supervisor/pull/593/files#diff-0240b66c1a20db854f3d6eacb71caa32R1031)