add samesite support

[mum-never-proud]

Resolves #85

[koriner]

@ScottHamper do you have any ETA on when this might get merged? :)

[ScottHamper]

Probably never, to be honest, though it is a well done PR! See #86

[koriner]

@ScottHamper Haha ok fair enough :) The only reason I asked is because this package (https://github.com/abersager/redux-persist-cookie-storage) uses yours as a dependency. Your points in #86 are valid though. We'll either write our own adapter or switch to something else with local storage.