Upgrade Manubot Rootstock version

[dhimmel]

Ref manubot/rootstock#65. Attempt a squash all method for updating manubot-rootstock codebase.

git checkout -b rootstock-branch rootstock/master
git rebase 4ae7a48b42446a9fc52ab0f71b0e5dce8af089fd
git checkout --theirs
git rebase --continue
git checkout upgrade
git merge rootstock-branch # should do --squash --no-commit in future
git checkout --ours ci/deploy.key.*
git add ci/deploy.key.*
# Manually fix and add other conflicts
git commit