Turned environemnt specific settings into function and added lambda function

- This is a massive change to fabfile_settings.py.sample, you must re-create
  yours.
- This finally allows to deploy to different servers (we had never tried that
  before and the old way didn't work, because many of the settings need to
  know the LOGIN_USER and that user will be different on different machines
  on Webfaction)
Released v2.0