Move to latest factory-boy.

Points the requirements file to the correct minimum version and updates
existing factories to point to new DjangoModelFactory class.

Also removes an extra factory from the Facebook tests.
Add tests for new models and banner creation process.
Fix various issues around setting up a new dev instance of the site.

- Add no extras to the banner admin BannerImageInline. Any blank extras
  cause the entire form to fail to submit.

- Add registration to JINGO_EXCLUDE_APPS to prevent admin logout 
  template from being rendered by Jinja.

- Update signal for default permissions to abort if the 
  can_share_website permission doesn't exist yet, which occurs when 
  creating an admin during the initial syncdb. Also adds tests for this
  signal.

- Update install docs to have correct paths.

- Use Pillow instead of PIL in requirements files; PIL has a hard time
  finding JPEG support on developer machines, whereas Pillow makes
  everything better. Servers can still use PIL if they wish.