Django piston is pretty old and does not work with django1.11 out of the box.
For the transition these are the changes required to get piston working

Start out by creating a new virtualenv, install the requirements, then change the following lines:

In piston/emitters.py:
    # instead of the original simplejson import
    import json as simplejson

    # instead of the DateTimeAwareJsonEncoder import
    from django.core.serializers.json import DjangoJSONEncoder as DateTimeAwareJSONEncoder

    # in ~186 replace the following line
    for f in data._meta.fields + data._meta.virtual_fields])
    # with this line
    for f in data._meta.fields + tuple(data._meta.virtual_fields)])

In piston/resource.py
    # in ~207 replace
    resp = HttpResponse(stream, mimetype=ct, status=status_code)
    # with this line
    resp = HttpResponse(stream, content_type=ct, status=status_code)