Fix digest auth when multiple headers are sent by the server

[jsternberg]

Digest authentication would fail if more than one header was sent as
part of the response. Look specifically for the "Digest" word as part of
the www-authenticate header.

This fixes issue #271.

[jnunemaker]

🆒 Could you add a spec to https://github.com/jnunemaker/httparty/blob/f7b84a97e9d08bf5e139121667b88385707426e2/spec/httparty/net_digest_auth_spec.rb to ensure we don't break this in the future? If so, happy to pull.

[jsternberg]

@jnunemaker do you want me to do anything else before merging? Do you want me to squash the commits?

[jnunemaker]

✨

[jsternberg]

Cool! Thanks.

If I may ask, do you know when you're going to perform another release?

[jnunemaker]

Not sure, but you can lock to the specific sha in master. I typically do that. Avoids lots of tiny releases.

[jsternberg]

OK. Do you think out would be possible to do another release? Gems can't lock onto a specific version and I have a gem that depends on this library that needs this patch. I can work around it in the final application with bundler, but it would be easier if I didn't have to.

[jnunemaker]

0.13.0 is out. Hopefully it causes no 🔥's. Lol.

[jsternberg]

Thanks!