Wraps Alexa Web Information Service.

Usage:

api = AwisApi(ACCESS_ID, SECRET_ACCESS_KEY)
tree = api.url_info("www.domain.com", "Rank", "LinksInCount")
elem = tree.find("//{%s}StatusCode" % api.NS_PREFIXES["alexa"])
assert elem.text == "Success"

or:

tree = api.url_info("www.domain.com", datetime.date(2012,1,1) )