Unable to create an album with Django 1.10

[sveetch]

Hi,

I've tried to use imagestore with Django 1.10.8, from the Django admin i can create an Image object but trying to create a new Album object result in an exception:

Traceback (most recent call last):
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/core/handlers/exception.py", line 42, in inner
    response = get_response(request)
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/core/handlers/base.py", line 249, in _legacy_get_response
    response = self._get_response(request)
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/core/handlers/base.py", line 187, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/core/handlers/base.py", line 185, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/contrib/admin/options.py", line 544, in wrapper
    return self.admin_site.admin_view(view)(*args, **kwargs)
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/utils/decorators.py", line 149, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/views/decorators/cache.py", line 57, in _wrapped_view_func
    response = view_func(request, *args, **kwargs)
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/contrib/admin/sites.py", line 211, in inner
    return view(request, *args, **kwargs)
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/contrib/admin/options.py", line 1509, in add_view
    return self.changeform_view(request, None, form_url, extra_context)
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/utils/decorators.py", line 67, in _wrapper
    return bound_func(*args, **kwargs)
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/utils/decorators.py", line 149, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/utils/decorators.py", line 63, in bound_func
    return func.__get__(self, type(self))(*args2, **kwargs2)
  File "/usr/lib/python3.5/contextlib.py", line 30, in inner
    return func(*args, **kwds)
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/contrib/admin/options.py", line 1450, in changeform_view
    self.save_related(request, form, formsets, not add)
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/contrib/admin/options.py", line 1031, in save_related
    self.save_formset(request, form, formset, change=change)
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/contrib/admin/options.py", line 1019, in save_formset
    formset.save()
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/forms/models.py", line 651, in save
    return self.save_existing_objects(commit) + self.save_new_objects(commit)
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/forms/models.py", line 784, in save_new_objects
    self.new_objects.append(self.save_new(form, commit=commit))
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/forms/models.py", line 928, in save_new
    obj.save()
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/db/models/base.py", line 796, in save
    force_update=force_update, update_fields=update_fields)
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/db/models/base.py", line 824, in save_base
    updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
  File "/home/emencia/projects/transinter/.envs/default/lib/python3.5/site-packages/django/db/models/base.py", line 880, in _save_table
    raise ValueError("Cannot force an update in save() with no primary key.")
ValueError: Cannot force an update in save() with no primary key.

This is effective with imagestore 3.0.0 and 3.1.0. Version 2.9.1 result in another error i assumed to be related to Django>1.9 support.