Support POST/Create Endpoints

[jpulec]

It'd be great for this library to start supporting post requests to allow the creation of objects at the available endpoints.

[io-ma]

@alecraso @jpulec Hi there, speaking of POST or say, PATCH, did you guys notice this really weird behavior when you want to send numbers?
Let's say I want to patch an offer and I need to write salary, bonus, equity blah.
All the other offer details like custom fields or stuff, usually strings - write back just well. Numbers end up empty.
Using postman works so I wonder if it's just me or you noticed it too.
L.E. Nevermind, it was my wrong approach.