Add samesite cookie option (fixes #212)

[schneider8357]

Fixes #212

[ahopkins]

Awesome. This is a good add. Thank you.

[ahopkins]

I didn't check the problems with the tests, but run make black if its linting.

[schneider8357]

I didn't check the problems with the tests, but run make black if its linting.

The build failed because I forked the main branch, which was failing the Travis build as well.

[ahopkins]

I didn't check the problems with the tests, but run make black if its linting.

The build failed because I forked the main branch, which was failing the Travis build as well.

Yikes. I better go check that out then.

[schneider8357]

I didn't check the problems with the tests, but run make black if its linting.

Still, I ran make black and this was the output:
(isort output was ommited because it didn't fix any of the files modified in this PR)

$ make black
black ./ -l 79 --safe
reformatted /home/lucas/sanic-jwt/setup.py
reformatted /home/lucas/sanic-jwt/sanic_jwt/configuration.py
reformatted /home/lucas/sanic-jwt/sanic_jwt/authentication.py
reformatted /home/lucas/sanic-jwt/tests/conftest.py
reformatted /home/lucas/sanic-jwt/tests/test_configuration.py
reformatted /home/lucas/sanic-jwt/tests/test_claims.py
reformatted /home/lucas/sanic-jwt/tests/test_endpoints_cbv.py
reformatted /home/lucas/sanic-jwt/tests/test_endpoints_basic.py
reformatted /home/lucas/sanic-jwt/tests/test_endpoints_init_on_bp_single.py
reformatted /home/lucas/sanic-jwt/tests/test_exceptions.py
reformatted /home/lucas/sanic-jwt/tests/test_user_secret.py
All done! ✨ 🍰 ✨
11 files reformatted, 69 files left unchanged.

And of the 4 files that I changed in this PR, only configuration.py was reformatted (and it was a docstring on line 252 unrelated to this issue), so I don't think that it will be a problem.

[schneider8357]

Regarding the tests, I did modify tests/test_endpoints_cookies.py. But I only did minor changes, mostly based on the other cookie flags' tests.

[Paladiamors]

While not urgent. I am curious about the status of this as I'd like to get rid of the samesite cookie warnings if possible

[ahopkins]

Let's get the tests passing and then merge/release.

[schneider8357]

Sadly, I can't do anything about the Travis build failing.

[ahopkins]

Sadly, I can't do anything about the Travis build failing.

Working on it

[Paladiamors]

@ahopkins Thanks for getting this merged!