CAS with LDAP in Docker

Uses gradle to build CAS 6.x

Docker Compose setup using a multi-stage build:

First stage builds a Docker image that:
- clones https://github.com/apereo/cas-overlay-template
- copies the src (local overlay) tree into it
- builds cas.war
Second stage runs CAS in a Docker container
- copies the directory etc/cas into the container at /etc/cas
- generates a self-signed keystore for CAS to use at startup
- copies the cas.war file from the first stage
- exposes port 8443
- runs /usr/bin/java -jar cas.war (using the embedded Tocmat server)

To build & run CAS in Docker type: docker-compose up --force-recreate. If you have changed anything in the Dockerfile, application.yml, or .env files, use this instead docker-compose up --force-recreate --build cas. If you want to be able to close the terminal and keep the container running, add the -d argument.
Open up a page at https://localhost:8443/cas/login and login as any user defined in the LDAP server
Type ctrl-c to exit (if not using -d), then type this to cleanup: docker-compose down --rmi all