check-sort-order unable to parse bcf files

go language does not have a bcf parser. Therefore, check-sort-order cannot check the sort order of `.bcf` files. 

Brent started a bcf parser in go, but it is not finished: https://github.com/brentp/bcf

1) For now:
  - skip check of sort order on bcf files

2) Future:
  - Add bcf parsing to check-sort-order 