When using the url arg to an Interceptor, if there is no port in the url an error happens

[cdent]

This fails:

def test_intercept_by_url():
    hostname = str(uuid4())
    url = 'http://%s/foobar' % hostname
    interceptor = Httplib2Interceptor(app=app, url=url)
    assert isinstance(interceptor, Interceptor)
    assert interceptor.app == app
    assert interceptor.host == hostname
    assert interceptor.port == 80
    assert interceptor.script_name == '/foobar'
    assert interceptor.url == 'http://%s:%s/foobar' % (hostname, port)
    assert interceptor.url == url

with

wsgi_intercept/interceptor.py:35: in __init__
    self._init_from_url(url)
wsgi_intercept/interceptor.py:70: in _init_from_url
    host, port = parsed_url.netloc.split(':')
E   ValueError: need more than 1 value to unpack

Basically that split needs to be safer.