[ReviewStack] Missing commit/PR versions on ReviewStack

[equetzal]

Context

Review Stack have a feature for switching the commit version:

Problem

Even if more versions are pushed and even detected by ReviewStack history, ReviewStack does not display this versions on the version dropbox and does only shows the very first version.

I've been able to reproduce this several times by sending a commit as a PR, amending the commit and the submitting it to Github again, the force pushed is accurately handled by github, but not by ReviewStack.

Expected Behavior

I would expect ReviewStack to load the last version instead of the first, as this makes more sense to review the last one. I would also expect ReviewStack to properly load the versions and allow switching between them as currently possible on Phabricator.

[sggutier]

I think it should be solved by #656

[ahornby]

probably also needs #684