Refactorings/improvements for requests

[ddudnik]

Hi,

Digging my way through the code, here are some changes/refactorings which I suggest:

• more generic 'make_request' method. Nicely isolates 'requests' lib (it's used only there now). All other methods use it to talk to API.
• generic 'get_results' and 'create_session' methods, so the overall API of all classes becoming more in sync
• improvement for handling errors in response

Cheers,
Denis

[ardydedase]

Thanks @ddudnik, the classes look much better than before.

Cheers,
Ardy