Create docker file for running server

[darcys22]

Users would be able to get up and running quicker if docker was set up

[davidalpert]

I can look into this.

We could easily add a Docker build target to the Makefile which would enable building the app from source into a container image, in a similar way as the xgo tool works.

For safety I imagine running mysql in Docker but configuring its data path to be outside the container in a path on host storage, primarily so that the ledger data would persist across mysql container restart. On a Mac this could look like this article (How to Run MySQL in a Docker Container on macOS with Persistent Local Data
and I'm sure that there would be linux and windows configuration equivalents)

docker-compose allows defining multiple docker containers (e.g. a mysql container and a godbledger container and eventually another for the web frontend if needed) in a single docker-compose.yml file so that the app could be started inside Docker like this:

git clone repo
cd into repo
./utils/configure-local-storage-for-docker-mysql.sh
docker-compose up

(or something like that)

[davidalpert]

wound up iterating a while futzing around with file and group ownership permissions for files created by a container running in docker on a volume mount on the host machine.

finally switched gears to my original idea and used docker-compose to start up and configure a mysql container.

PR #110 is ready for review