GitLab

Previously, it only checked the major version number (this was a
regression as a result of switching to Git).

Also abstracted version checking to a testable CheckVersion function,
and added tests for ParseVersion and CheckVersion.

Also added better documentation everywhere about the format of the
--check-version option.

BUG=406993

Review URL: https://codereview.chromium.org/506863005

Cr-Commit-Position: refs/heads/master@{#296618}