remove redundant use of recurring_failed
Fixed code style.
Added logger to describe process flow.
Added missing logger.

Conflicts:

	paypal/standard/pdt/views.py
Added copy value from txn_id field to tx field.
Added log to expose postback response

Conflicts:

	paypal/standard/models.py
Added more log entries to expose endpoint request.
Changed transaction id field in postback parameters.
Added log for success and fail staus from postback.
Fixed indent.