Test nginx as part of build

Dockerfile

@@ -23,7 +23,7 @@ RUN pip install --no-cache-dir -r requirements.txt \
 COPY nginx.conf /etc/nginx/sites-enabled/app.conf
 
 # Remove default config and Test nginx
-RUN rm /etc/nginx/sites-enabled/default && nginx -t
+RUN rm /etc/nginx/sites-enabled/default && nginx -t && service nginx start
 
 # Copy the rest of the application code into the container
 COPY . .