re-fix upload gallery

[petry]

Traceback (most recent call last):

  File "/opt/projects/donnatune/virtualenv/local/lib/python2.7/site-packages/django/core/handlers/base.py", line 115, in get_response
    response = callback(request, *callback_args, **callback_kwargs)

  File "/opt/projects/donnatune/virtualenv/local/lib/python2.7/site-packages/newrelic-2.0.0.1/newrelic/api/object_wrapper.py", line 257, in __call__
    self._nr_instance, args, kwargs, **self._nr_kwargs)

  File "/opt/projects/donnatune/virtualenv/local/lib/python2.7/site-packages/newrelic-2.0.0.1/newrelic/hooks/framework_django.py", line 485, in wrapper
    return wrapped(*args, **kwargs)

  File "/opt/projects/donnatune/virtualenv/local/lib/python2.7/site-packages/django/contrib/admin/options.py", line 372, in wrapper
    return self.admin_site.admin_view(view)(*args, **kwargs)

  File "/opt/projects/donnatune/virtualenv/local/lib/python2.7/site-packages/django/utils/decorators.py", line 91, in _wrapped_view
    response = view_func(request, *args, **kwargs)

  File "/opt/projects/donnatune/virtualenv/local/lib/python2.7/site-packages/django/views/decorators/cache.py", line 89, in _wrapped_view_func
    response = view_func(request, *args, **kwargs)

  File "/opt/projects/donnatune/virtualenv/local/lib/python2.7/site-packages/django/contrib/admin/sites.py", line 202, in inner
    return view(request, *args, **kwargs)

  File "/opt/projects/donnatune/virtualenv/local/lib/python2.7/site-packages/django/utils/decorators.py", line 25, in _wrapper
    return bound_func(*args, **kwargs)

  File "/opt/projects/donnatune/virtualenv/local/lib/python2.7/site-packages/django/utils/decorators.py", line 91, in _wrapped_view
    response = view_func(request, *args, **kwargs)

  File "/opt/projects/donnatune/virtualenv/local/lib/python2.7/site-packages/django/utils/decorators.py", line 21, in bound_func
    return func(self, *args2, **kwargs2)

  File "/opt/projects/donnatune/virtualenv/local/lib/python2.7/site-packages/django/db/transaction.py", line 223, in inner
    return func(*args, **kwargs)

  File "/opt/projects/donnatune/virtualenv/local/lib/python2.7/site-packages/django/contrib/admin/options.py", line 1007, in add_view
    self.save_model(request, new_object, form, False)

  File "/opt/projects/donnatune/virtualenv/local/lib/python2.7/site-packages/django/contrib/admin/options.py", line 740, in save_model
    obj.save()

  File "/opt/projects/donnatune/virtualenv/src/django-photologue/photologue/models.py", line 260, in save
    gallery = self.process_zipfile()

  File "/opt/projects/donnatune/virtualenv/src/django-photologue/photologue/models.py", line 265, in process_zipfile
    if os.path.isfile(self.zip_file.path):

  File "/opt/projects/donnatune/virtualenv/local/lib/python2.7/site-packages/django/db/models/fields/files.py", line 59, in _get_path
    return self.storage.path(self.name)

  File "/opt/projects/donnatune/virtualenv/local/lib/python2.7/site-packages/django/core/files/storage.py", line 85, in path
    raise NotImplementedError("This backend doesn't support absolute paths.")

NotImplementedError: This backend doesn't support absolute paths.