Added a "canonical name" field to ITIS

Since ITIS contains scientificNames both with and without authority information, it can be tricky to reconcile data against this file. To simplify this, I've added a canonical name field which always contains all the parts of the scientificName *except* authority. The scientificName field remains.

Furthermore, I've created a separate executable which only processes ITIS results. It is identical to the main dwca-hunt.rb file, except for the steps which are commented out.