Multiple project groups.

Jeepyb now pulls all project groups listed in review.projects.yaml
to check for bugs or blueprints. This is to support multiple
project group membership in storyboard. If 'groups' is not found,
it will fallback to the legacy 'group' or the short project name,
wrapped in an array.

Change-Id: I5f6d09fce609f387b089840f3903303869f33767
Merge "Multiple project groups."