This concludes the saga that began with commit c053bdbd, migrating away
from using gob-encoded big.Float values in the database to using
integers with an implied number of decimal places.
Nothing is using or accessing or expecting the _gob columns to exist
anymore. The transition code and the migration chore are gone. All that
remains is to drop the columns.
Change-Id: I9b15ee52f7781510a6dc91cf7c54f7f9022b1210
