cubicweb-fastimport #5359084 don't choke on insertion of NULL bytes fields [done]

priorityimportant
typebug
done in0.3.0
load0.100
load left0.000
closed by#b80058624a42 Entities: allow insertion of NULL bytes (closes #5359084)
patchEntities: allow insertion of NULL bytes (closes #5359084) [applied]