Add environment var support for image version

Added support to define the version of the container to run via
environment variables.

Closes: #12

Author: Derek Murawsky

run.sh

@@ -17,9 +17,8 @@
 
 set -e
 
-VERSION="latest" # can be set to a specific version tag from docker hub, such as "1.25.5", or "alpine"
-IMAGE="linuxserver/docker-compose:$VERSION"
-
+DOCKER_COMPOSE_CONTAINER_VERSION="${DOCKER_COMPOSE_CONTAINER_VERSION-latest}" # can be set to a specific version tag from docker hub, such as "1.25.5", or "alpine"
+IMAGE="linuxserver/docker-compose:$DOCKER_COMPOSE_CONTAINER_VERSION"
 
 # Setup options for connecting to docker host
 if [ -z "$DOCKER_HOST" ]; then
@@ -68,4 +67,4 @@ if docker info --format '{{json .SecurityOptions}}' 2>/dev/null | grep -q 'name=
 fi
 
 # shellcheck disable=SC2086
-exec docker run --rm $DOCKER_RUN_OPTIONS $DOCKER_ADDR $COMPOSE_OPTIONS $VOLUMES -w "$(pwd)" $IMAGE "$@"
+exec docker run --rm $DOCKER_RUN_OPTIONS $DOCKER_ADDR $COMPOSE_OPTIONS $VOLUMES -w "$(pwd)" $IMAGE "$@"