Summary:
There's now an `updateLevel` that can be set in the config file.
It has the valid values of "major", "minor", "patch", and "commit". By
default it upgrades on the "patch" level.
If you want to be on the bleeding edge, manually change the config file to
add `updateLevel: 'commit'`
Test Plan: A new `auto-update-manager-spec` :)
Reviewers: bengotow
Reviewed By: bengotow
Differential Revision: https://phab.nylas.com/D1567