Add ability to limit updates in migrations.
To make sure things are looking okay in the migration, we can run it
with a limit of something like 10 or 30. We can look at the output of
the migrated columns to see if they are correct. This should have no
effect on subsequently running the full migration.
Change-Id: I2c74879c8909c7938f994e1bd972d19325bc01f0
Value attribution codes were converted into UUIDs and stored
in the users, projects, api_keys, bucket_metainfos, and
value_attributions tables in the partner_id column. This
migration will lookup the appropriate partner name associated
with each of these UUIDs, and store the partner name directly
in the user_agent column within each table. If no corresponding
partner name exists for a partner_id, the partner_id value will
be stored instead.
Add migration for users table with tests.
Change-Id: I61254d9b81c474e76bcfc1c8cd863697c6ef44b6
