change type of iri fields to text

Of course if an iri-field for 255 chars
is too short in the alternative_iris tables it is
too short for every table. So this changes the type
to text for all remaining tables which contain an
iri field.
fix entitytest for text-iri field.
Merge pull request #670 from ontohub/534-change_iri_type_for_all_tables

change type of iri fields to text