External Tracking Checklist Item Statuses

[rbrady]

As a user, filch should check the status of external trackers and update the list item so card reviewers can know the status without having to open the link. This pertains to gerrit urls to update the checklist item with status[1] or check them off if the review is landed or abandoned.

[1]https://review.openstack.org/#/c/#####/ [+2 Code-Review] [-1 Zuul]