Optional Response Params need a "Revision" XML tag

[prabhathn]

Propose adding this at the following line: https://github.com/thelinuxkid/pyusps/blob/master/pyusps/address_information.py#L133

    # Documentation refers to this as "Version" - it is an option to return all optional data as well
    version_el = etree.Element('Revision')
    version_el.text = '1'
    root.append(version_el)

Without this code, the USPS API only returns the Address, City, State, Zip. By including this Revision tag, we get all the optional params as well.

[thelinuxkid]

Thanks. Can you make a PR please?

[prabhathn]

Sure! Here you go: #8

Thanks!