LP#1067823: Genre links launch subject search

LP#1067823: Genre links launch subject search

And genres are not subjects.  So now we will index genres in the identifier
class and teach the tpac to build links appropriately.  Genre is herein
defined as data in tags 655 or 659 (as the tpac currently thinks), restricted
to subfields [abvxyz], per LoC documentation.

To test:

[1] Apply the update and run the partial reingest as suggested
    by the upgrade script.
[2] In the public catalog, navigate to a record that has one
    or more 655 fields.  Click on one of the genre links and
    verify that it retrieves records sharing that genre heading.

Signed-off-by: Mike Rylander <mrylander@gmail.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>