python3 compatibility
update version from 0.5 to 0.6
added coverage
changed the tox.ini
added --with-xunit to the tox.ini testenv:cover
removed the testenv:cover from tox.ini
changed the field tests.
added collection test
moved the serializer registry to utils. Added mor colletion tests.
added missing sort for collections.
fixed the multiple sort for collections.
added collection tests.
added the unknown field error
CollectionSerializer validation default is now False
added tests for django support.
renamed test methods
added a django import check
removed not used logging