Updates pre-population information for partners
Merge branch 'master' of github.com:gocardless/gocardless-python

* 'master' of github.com:gocardless/gocardless-python:
  Stylistic improvements
  Adds support for Bill#retry
  Link readme header to docs
  Bump version to v0.2.1
  python 2.6 compatability fixes
  Update changelog
  Bump version to 0.2.0
  fix tests and bump version to 0.1.6
  dont check if setup_fee is positive, to match the validation in SubscriptionParams
  preauth setup_free
  Refactor as per suggestions
  Add an alias to new_preauthorization_url.
  Update changelog
  Some pep8
  Move constants to module level
  Bump version number to 0.1.5
  Use `self` instead of class name
  Remove testing code
  Update README header
  Update logo