Add optional column oc_comments.reference_id

apps/settings/lib/Controller/CheckSetupController.php

apps/settings/tests/Controller/CheckSetupControllerTest.php

core/Application.php

core/Command/Db/AddMissingColumns.php

core/Command/Db/AddMissingIndices.php

core/Migrations/Version13000Date20170718121200.php

core/js/setupchecks.js

core/js/tests/specs/setupchecksSpec.js

core/register_command.php

lib/private/DB/MissingColumnInformation.php

lib/public/IDBConnection.php