Review Board 3.0 began tracking which users made changes to review

requests, so that special users could modify a review request without

making it appear as if the changes came from the original owner, and to

allow changing the owner of a review request. This caused a regression

in the behavior for RBTools's --submit-as, where the review request

would be created with the specified user but published with (and

notifications going out as) the logged in user.
This change restores the original behavior. The initial publish of a

review request now always comes from the owner of the review request,

rather than the logged in user. Since --submit-as only works for the

initial creation, this makes things work how they did in previous

releases.
A new publish_as_owner=1 option was also added when publishing drafts,

which forces this same logic on future updates. This will allow

automation scripts to update review requests fully on behalf of the

owner, which wasn't possible until now.
Unit tests were added for these new changes.

All unit tests pass.
Manually posted to my server using --submit-as=... --publish. Saw that

the notifications went out as the correct user.
Temporarily modified RBTools to set publish_as_owner. Posted with and

without it. Saw that the notifications were sent out as the correct user

in both cases.