Add --force option to migrator, to run the migration again.
Add --force option to migrator, to run the migration again.

For instance after adding a different akonadi resource, which turns out to
have non-migrated tasks as well...

sandsmark/zanshin,kolab-groupware/zanshin,sandsmark/zanshin,sandsmark/zanshin,kolab-groupware/zanshin,kolab-groupware/zanshin