Modified columns to set to not null and default val of ''
Modified columns to set to not null and default val of ''

refs #638

- Should fix the problem encountered in ticket #638 but need to be tested.
  Modifications brought as well on db as on createtable.sql file

naturalsciences/Darwin,naturalsciences/Darwin,eMerzh/Darwin,naturalsciences/Darwin,eMerzh/Darwin,eMerzh/Darwin