Revision 1914922

Combine .start() and .finish() into a single deliver() method.

* tools/hook-scripts/mailer/mailer.py:
  (OutputBase.send): rename BASIC_SUBJECT to SUBJECT_LINE, as that is
    the appropriate name. Use the new .deliver() method rather than
    the old start/finish.
  (OutputBase.deliver): new method, to be overridden.
  (OutputBase.start, OutputBase.finish): removed
  (MailedOutput.start): renamed to ...
  (MailedOutput.get_prefix): ... this
  (SMTPOutput.finish): renamed to ...
  (SMTPOutput.deliver): ... this. Fetch the prefix and include it
    before the BODY, when sending the email.
  (StandardOutput.start, StandardOutput.finish): removed in favor of ...
  (StandardOutput.deliver): ... this. Combine the above two methods to
    produce the prefix and BODY on stdout.
  (PipeOutput.finish): ... removed in favor of
  (PipeOutput.deliver): this. New params. Get the prefix and push it
    into the pipe before the BODY.