Do not treat auto_generated messages as published messages

Do not treat auto_generated messages as published messages.

This is to ensure that no matter what logging is done before (reviewers added, CQ checked, etc), the first published 
message contains the diff and does not contain 'Re:'.


As part of this CL I also reverted the workarounds done in:
* https://codereview.appspot.com/126680043/ (Delay the creation of the reviewers change log message to avoid "Re:" subject on initial comment)
* https://codereview.appspot.com/133880043/ (Fix initial diff email feature by calling put() on auto-generated Messages later)


This CL replaces <a href='https://code.google.com/p/rietveld/source/detail?r=af712bf0708b4ec1043c2783e197a75959a40006&name=chromium'>https://code.google.com/p/rietveld/source/detail?r=af712bf0708b4ec1043c2783e197a75959a40006&name=chromium</a> with a better approach.


Tested with the following CLs:
* https://skia-codereview-staging.appspot.com/6841001/ (testing add-reviewers-in-edit-then-publish)
* https://skia-codereview-staging.appspot.com/1871001/ (testing add-reviewers-in-publish)
* https://skia-codereview-staging.appspot.com/8831001/ (testing check-cq-then-publish)


BUG=<a href='https://code.google.com/p/chromium/issues/detail?id=407382'>chromium:407382</a>

[jrobbins (corp), 2014-08-28 20:43:36]

lgtm

You might want to note in the CL description that this replaces
https://code.google.com/p/rietveld/source/detail?r=af712bf0708b4ec1043c2783e1...
with a better approach.

[rmistry, 2014-08-28 20:45:29]

On 2014/08/28 20:43:36, jrobbins (corp) wrote:
> lgtm
> 
> You might want to note in the CL description that this replaces
>
https://code.google.com/p/rietveld/source/detail?r=af712bf0708b4ec1043c2783e1...
> with a better approach.

Done.

[rmistry, 2014-08-28 20:47:51]

Submitted as
https://code.google.com/p/rietveld/source/detail?r=1eebc533dbbcdb65ec222b07ca...

[rmistry, 2014-08-28 20:49:02]

Whenever this is deployed (to a non-default version), lets try to test all edit
+ publish flows we can.