add Phone and children

[isybuy]

Hello, I'm using your library for my project and the Phone in the Address class doesn't conform to CXml practice, you're sending a string when we need more fields (according to https://xml.cxml.org/current/cXMLReferenceGuide.pdf)

<Phone name="work">
    <TelephoneNumber>
        <CountryCode isoCountryCode="BE" />
        <AreaOrCityCode />
        <Number>1151869655</Number>
    </TelephoneNumber>
</Phone>

Can you add it please ? 😎

[mathielen]

Hey there!

You're welcome to add a PR with the changes you propose. Happy to merge it :)