== FileTransferMixin ==
FileTransferMixin is a module that you can include in a library.  It will support various mechanisms long-term, but
for now is focused on SFTP servers.

- sftp_send(key, remote_location, local_file_path)
- sftp_fetch(key, remote_path, local_path)

- It expects an ENV variable named FILE_TRANSFER_MIXIN_CONFIG_PATH to be set.
- It expects a yml configuration file in FILE_TRANSFER_MIXIN_CONFIG_PATH that looks like the following:

sftp:
  some_key:
    server: sftp.matrix.com
    username: neo
    password: the_one

Then in a class, you would deal with it thusly:

class SomeClass
  include FileTransferMixin

  # Some method that uploads a file
  def some_method
    sftp_send(:some_key, remote_path, local_path)
  end

  # Some method that fetches a file
  def fetch_method
    sftp_fetch(:some_key, remote_path, local_path)
  end
end

== Motivation ==
We have quite a few libraries that interact with remote SFTP servers, and inevitably they share massive swathes of code
that should be unnecessary.  This intends to be a mixin to make the easy things extremely easy.