Re-check when the contributors file is updated

[pelson]

Story:

When the contributors list gets updated
I want all stories that have been marked as needing a CLA to be re-checked
So that each PR continues to represent the true state of the contributors list.

Note:
Perhaps we do this by searching for all PRs that have a label "Blocked: CLA needed"

[pelson]

Simply removing the label on a PR gets an individual PR re-check. Would still be great to have this universally though.