Update build.sh (#4)

Better variable check

Author: chayim

build.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 
-if [[ -n "${DOCKER_ACCESS_TOKEN}" ]]; then
+if [[ -z "${DOCKER_ACCESS_TOKEN}" ]]; then
   echo $DOCKER_ACCESS_TOKEN | docker login --username=$DOCKER_USERNAME --password-stdin
 fi
 
@@ -16,4 +16,4 @@ docker-compose exec -T node-1 "/opt/join_node.sh"
 docker-compose exec -T node-2 "/opt/join_node.sh"
 
 ## Create DB ##
-docker-compose exec -T master-node "/opt/create_db.sh"
+docker-compose exec -T master-node "/opt/create_db.sh"