Incompatibility with supported Django versions

[cormier]

Tox tests against Django 1.5 up to Django 1.8

• https://github.com/emory-libraries/eulxml/blob/master/tox.ini#L12

Those Django versions are not longer supported by the Django project team and receiving security fixes.

• https://www.djangoproject.com/download/

Only Django 1.11 and 2.x are supported at the moment.

However eulxml is incompatible with these versions: it uses a function, get_declared_fields, that has been deprecated and removed in Django 1.9

I believe we need to:

1. Determine what Python and Django versions we want to support:

I suggest dropping support for the following versions of python:

• 2.6 (python2 users are encouraged to migrate to 2.7)
• 3.3 (it has reached end of life)

I suggest dropping support for django 1.5, 1.6, 1.7, 1.8 and 1.9 and supporting only 1.10, 1.11, 2.0.

1.11 and 2.0 are the only officially supported versions.