Move model import down into methods (#11)

Work around import issues in Django 1.11 when djpyfs is imported early.

djpyfs/djpyfs.py

@@ -20,8 +20,6 @@ from django.conf import settings
 from fs.osfs import OSFS
 from fs.s3fs import S3FS
 
-from .models import FSExpirations
-
 
 if hasattr(settings, 'DJFS'):
     DJFS_SETTINGS = settings.DJFS  # pragma: no cover
@@ -56,6 +54,7 @@ def expire_objects():
     """
     Remove all obsolete objects from the file systems.
     """
+    from .models import FSExpirations
     objects = sorted(FSExpirations.expired(), key=lambda x: x.module)
     fs = None
     module = None
@@ -97,6 +96,7 @@ def patch_fs(fs, namespace, url_method):
         Returns:
             None
         """
+        from .models import FSExpirations
         FSExpirations.create_expiration(namespace, filename, seconds, days=days, expires=expires)
 
     fs.expire = types.MethodType(expire, fs)

setup.py

@@ -12,7 +12,7 @@ else:
 
 setup(
     name='django-pyfs',
-    version='1.0.6',
+    version='1.0.7',
     description='Django pyfilesystem integration',
     author='Piotr Mitros',
     author_email='pmitros@edx.org',