Add support for non urlencoded payloads

[MartijnBraam]

This pr allows the use of curl->post('example.php', json_encode($my_payload)); and unifies this behavior for post, put and patch

[amouhzi]

Hello,

There is a bug in your pull request.

Tests don’t pass.

[ErickTamayo]

When this will be implemented?

[amouhzi]

Hello @ErickTamayo,
You can do the necessary changes in you branch without needing to do a new pull request.
Then I can see tests results, and I will implement it if I see only one fail in the tests.
Thank you.

[ErickTamayo]

Sure, I'll do the changes by tomorrow or the saturday if @MartijnBraam doesn't do it first.

[amouhzi]

I reverted it. 5 failures with it.