Rewrote api to use requests library.

Works for the standard four http methods.
Figured it was easier to rewrite than fix the random bugs.
Also added Coupons.

The readme is now inaccurate.
Better exception handling _check_response
Moved resources out to other file
Kinda updated the README
SubResources seem to be working
Subresources work; all functionality done(?)
All resources and subresources added
Update README.md
Update README.md
some cleanup
Update README.md
Merge branch 'master' of https://github.com/bc-jackiehuynh/bigcommerce-api-python
Update README.md
Update README.md
Added example script
Added random test
Update README.md
Update README.md
Update README.md
Grouped imports into package