Add SPNEGO support

[Tagar]

As proposed in #55

Thank you.

Checklist

• Used a fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[ocefpaf]

Can you add a test for that functionality?

[Tagar]

@ocefpaf to test SPNEGO, I would need a spnego/kerberos-enabled web service to test that.. ideas if we have that available as part of CI?
Also, it's my first contribution here.. can you please send a pointer to some existing tests?
Thank you.

[ocefpaf]

I was not thinking about an elaborated test like that 😄. Just a curl -V like you had in the issue and check for the appropriated string. It can be a command test in the recipe.

[jakirkham]

Also this could use a build number bump 🙂