Improve logging

[knazart]

We need to improve logging as in some cases it's hard to debug issues for our clients.

For example, if we get a "Unexpected error. A Square Order Response was not returned." error we can't debug easily because the response itself (response from the API) didn't get logged, thus we don't have any other information but the above string.

We have this issue because in this case we didn't get any of the promised responses described in the docs, or the response data was not represented in the object form.