Support django 2.0

.travis.yml

@@ -40,8 +40,8 @@ notifications:
 install:
   - travis_retry pip install pep8==1.7.0
   - travis_retry pip install python-coveralls
-  - travis_retry pip install -e .
   - travis_retry pip install $DJANGO --upgrade
+  - travis_retry pip install -e .
 script:
   - coverage run --source=stream_django setup.py test
 after_script:

README.md

@@ -110,7 +110,7 @@ Below shows an example how to set things up if your user field is called author.
 ```python
 class Tweet(models.Model, Activity):
     created_at = models.DateTimeField(auto_now_add=True)
-    author = models.ForeignKey(settings.AUTH_USER_MODEL)
+    author = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
 
     @property
     def activity_actor_attr(self):

setup.py

@@ -6,8 +6,8 @@
     README = readme.read()
 
 requirements = [
-    'django>=1.5,<2.0',
-    'stream-python>=2.8.0',
+    'django>=1.5,<2.1.0',
+    'stream-python>=2.8.1',
     'pytz'
 ]
 

stream_django/tests/test_app/migrations/0001_initial.py

@@ -18,7 +18,7 @@ class Migration(migrations.Migration):
             fields=[
                 ('id', models.AutoField(verbose_name='ID', serialize=False, auto_created=True, primary_key=True)),
                 ('created_at', models.DateTimeField(auto_now_add=True)),
-                ('author', models.ForeignKey(to=settings.AUTH_USER_MODEL)),
+                ('author', models.ForeignKey(to=settings.AUTH_USER_MODEL, on_delete=models.CASCADE)),
             ],
             options={
             },

stream_django/tests/test_app/models.py

@@ -4,7 +4,7 @@
 
 
 class Pin(models.Model, Activity):
-    author = models.ForeignKey(settings.AUTH_USER_MODEL)
+    author = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
     created_at = models.DateTimeField(auto_now_add=True)
 
     @property