Session cookie setting overhaul

[aleshasam]

I suggest transferring the ability to manage cookie settings to developers, this may be useful in a situation of developing the backend on the server and the interface locally. I also think that other developers will be able to find more uses.

[taylorotwell]

I am closing this pull request because it lacks sufficient explanation, tests, or both. It is difficult for us to merge pull requests without these things because the change may introduce breaking changes to the framework.

Feel free to re-submit your change with a thorough explanation of the feature and tests - integration tests are preferred over unit tests. Please include it's benefit to end users; the reasons it does not break any existing features; how it makes building web applications easier, etc.

Thanks!