Added clear() exist() and contributing section to README.md

[mostafaebrahimi]

@rafaelcamargo Hey buddy! I added these two functions those uses your implemented functions.

[rafaelcamargo]

Hello @mostafaebrahimi!

When I created glorious-cookie, my master purpose was to bring the simplest and tiniest alternative to the existing packages which handle cookies. That's the tagline on the glorious-demo page , indeed:

The simplest and tiniest library to handle cookies.

That said, I can't see value on the new methods proposed. exist() can be easily achieved with get(), and clear() seems not to be the case in real life. This method will accidentally remove cookies that the user don't necessarily knows like a third party cookie used for metrics, for example.

Conclusion is: Since simple and tiny are the master purpose of this lib, I will hardly add any other method to this.

Regarding the README contribution, that will be nice 👍

[mostafaebrahimi]

Yes. you are right 👍