ACTION-2140 - Check google library for support of extension numbers in telephone numbers

All,

So a quick look at the Google library seems to confirm that they support
parsing extensions. See for example [1]. The comment says:

    // There are three regular expressions here. The first covers RFC 3966
format, where the
    // extension is added using ";ext=". The second more generic one starts
with optional white
    // space and ends with an optional full stop (.), followed by zero or
more spaces/tabs/commas
    // and then the numbers themselves. The other one covers the special
case of American numbers
    // where the extension is written with a hash at the end, such as "-
503#"

So that tells us that, but I am not sure where we left this question last
time we talked about phone numbers.

-Erik

[1]
https://github.com/googlei18n/libphonenumber/blob/master/java/libphonenumber/src/com/google/i18n/phonenumbers/PhoneNumberUtil.java#L331