Feature: `status` Column on Graders to Indicate Orca Usage

[williams-jack]

Description

Once Orca results can be rendered in the UI, we need a way to store image build information about the Graders as well as know if we should render this information on Bottlenose. This can be accomplished by having a JSON field on Graders in the DB, detailing if the grader is using Orca and what the status of its image build is on the Orca web server.

Changes Made

• Migration to add status column to the Graders table.
  • Default value of { useOrca: false }, as currently using Orca is not assumed by graders.
• schema.rb updated to reflect changes.

[blerner]

The migration you added creates a nullable column, which is fine...so the default of null is fine as well, and indicates no knowledge of orca. (We don't need to store a non-null default for all the old graders; they just don't care about this... It will be an interesting migration, sometime in the future, to update them all to run via orca...)

[williams-jack]

Changes obsolete by #275