Update docker images to modify mysql configuration

Dockerfiles are updated with two key changes:
- use streamline's official images as a base
- replace two files related to mysql configuration

A README.md file is added to the docker folder which details the changes, but
the key difference is to limit binary logs to only the `streamline` database.
This prevents additional system databases from being included, which the
database sync tools do not (yet) support.

An unrelated bugfix corrects the docker-compose image tag, specifying 'latest'
instead of a previously hard-coded version.

root/var/signalytic/clientapps/streamline/streamline-emr/docker-compose.yml

@@ -1,7 +1,7 @@
 version: '3.9'
 services:
   streamline-emr:
-    image: ${IMAGE:-streamline-emr:2.0}
+    image: ${IMAGE:-streamline-emr:latest}
     container_name: ${CONTAINER_NAME}
     volumes:
         - "${DATA_DIR}:/var/lib/mysql"

root/var/signalytic/clientapps/streamline/streamline-emr/template.env

@@ -2,4 +2,4 @@ COMPOSE_PROJECT_NAME=streamline-emr-{{INSTANCE_NAME}}
 CONTAINER_NAME=streamline-emr-{{INSTANCE_NAME}}
 DATA_DIR=/var/signalytic/clientapps/streamline/streamline-emr/instances/{{INSTANCE_NAME}}/data
 APP_PORT={{INSTANCE_PORT}}
-#IMAGE=streamline-emr:2.0
+#IMAGE=streamline-emr:latest