Updating form_params to json

[eporama]

This is a PR to fix #81

[coveralls]

Coverage decreased (-0.01%) to 99.068% when pulling e07e4de on eporama:81-x-www-form-encoded-to-json into 28e88b5 on typhonius:master.

[typhonius]

Thanks @eporama for the deep dive into this. One question - do you think that based on this behaviour we need some kind of test for encoding and content-type or would this be covered by Guzzle's tests?

[eporama]

I don't know that we would… I'm not sure that it's any more testable than using form_params was… but I could be wrong on that. I'm learning a lot about these things today…

[typhonius]

Thanks for that, I'll have a peek over the next couple of days to see if I can add anything else here - if not I'll merge.

[typhonius]

Looking at this again, we already check that json (not form_params) are within the options array passed to Guzzle so I'm happy to not include any additional tests (since it should be covered in Guzzle).