Remove requests from dependencies

It doesn't seem to be used used anywhwere...
Only include Oscar and Recurly deps in setup.py

You don't need them in requirements.txt as well.
Add makefile for setting up project for contributing
Include Oscar's apps when running tests

The tests still don't pass yet tho :(
README is RST not MD

Make a few improvements also.
Merge pull request #1 from codeinthehole/small-tweaks

Small tweaks