refactor: remove some 'max_length=255' to be more DRY feat: example of making an OpaqueKeyField case_sensitive (modulestore_migrator) test: update test now that we're using case-insensitive collation on SQLite
refactor: remove some 'max_length=255' to be more DRY feat: example of making an OpaqueKeyField case_sensitive (modulestore_migrator) test: update test now that we're using case-insensitive collation on SQLite