fix local docker build and run

[jj-style]

Fix #354 unable to build docker container.

Add gulp to normal node dependencies as currently not installed with npm install --production flag but is necessary to run with npm start in the container.
Add dockerignore file to ignore node_modules and other larger directories which slow down the docker build from COPY . /usr/src/app.
Bind on 0.0.0.0 so Raneto can be accessed from outside the container if the port is forwarded.

I have tested mounting a local content folder into the container at /usr/src/app/example/content and it works as expected.

[ryanlelek]

Thanks!
Yes, that will solve the issue for now.

This builds the assets with gulp in the Docker image.
In the future, we'll move to generating the assets outside Docker and copy them into the image.

A quick note:
The reason for the && is to perform 2 commands with one RUN Dockerfile statement.
Every RUN statement creates a new Docker image "layer" so 2 RUNs gives 2 layers.

[jj-style]

Thanks for the feedback!
Yeah I thought it made sense for Docker to handle pulling and building all dependencies inside the container.

Good point on the two commands in one, happy to combine that back to one.

We can also get clever with Docker and copy the package.json and do npm install and the gulp stuff before copying the source code to make use of Docker caching the image layers to make the builds faster!