Add Chapter One, Lecture 3 demo files

Chapter_One/Lecture_3_Demo/myapp/Dockerfile

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+FROM python:3.5
+
+COPY . /app
+WORKDIR /app
+
+RUN pip install -r requirements.txt
+
+CMD ["python", "-u", "server.py"]

Chapter_One/Lecture_3_Demo/myapp/requirements.txt

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+tornado

Chapter_One/Lecture_3_Demo/myapp/server.py

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+import tornado.ioloop
+import tornado.web
+
+
+class MainHandler(tornado.web.RequestHandler):
+    def get(self):
+        self.write("Hello, world\n")
+        print(self.request)
+
+
+def make_app():
+    return tornado.web.Application([
+        (r"/", MainHandler),
+    ])
+
+
+if __name__ == "__main__":
+    app = make_app()
+    app.listen(8888)
+    tornado.ioloop.IOLoop.current().start()
+