fixes issue where config.ext was not set (FCREPO-2347) (#13)
fixes issue where config.ext was not set (FCREPO-2347) (#13)

* add extension mapping based on rdflang

* delete print used for debugging

* fixed wording of error messages

bseeger/fcrepo-import-export-verify,fcrepo4-labs/fcrepo-import-export-verify,jwestgard/fcrepo-import-export-verify