fix bug when creating entities

Using AutoFields solve the problem. That way we custom fields (such as
id_num) used as primary key are auto incremented. The problem was that
using PositiveInteger, the field was not being set manually nor
incremented automaticaly.
rename FixDjangoORM

since it has nothing to do with populate
add dcid logo to index and navbar

also removed the "brand" part of the navbar from the "navbar-content"
block. That way the brand is independent of the page content.