Update Docker Compose file format 3

compose/demo/django/.gitignore

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+django_example

compose/demo/django/Dockerfile

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+FROM python:3
+ENV PYTHONUNBUFFERED 1
+RUN mkdir /code
+WORKDIR /code
+ADD requirements.txt /code/
+RUN pip install -r requirements.txt
+ADD . /code/

compose/demo/django/docker-compose.yml

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+version: "3"
+services:
+
+  db:
+    image: postgres
+
+  web:
+    build: .
+    command: python3 manage.py runserver 0.0.0.0:8000
+    volumes:
+      - .:/code
+    ports:
+      - "8000:8000"
+    links:
+      - db

compose/demo/django/manage.py

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+#!/usr/bin/env python
+import os
+import sys
+
+if __name__ == "__main__":
+    os.environ.setdefault("DJANGO_SETTINGS_MODULE", "django_example.settings")
+    try:
+        from django.core.management import execute_from_command_line
+    except ImportError:
+        # The above import may fail for some other reason. Ensure that the
+        # issue is really that Django is missing to avoid masking other
+        # exceptions on Python 2.
+        try:
+            import django
+        except ImportError:
+            raise ImportError(
+                "Couldn't import Django. Are you sure it's installed and "
+                "available on your PYTHONPATH environment variable? Did you "
+                "forget to activate a virtual environment?"
+            )
+        raise
+    execute_from_command_line(sys.argv)

compose/demo/django/requirements.txt

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+Django>=1.8,<2.0
+psycopg2