Change sequence names used (remove 'no_gec')

Follows from Allen!1112 (merged) and Moore!2631 (merged) (test together)

There are failing tests from the changes in Allen. These failures happen because we changed some sequence file names that were used by the tests (no longer contain 'no_gec'). So, I just fix the names to allow the test to use the correct files.

I also fixed the README example to use the modified sequence name now