update the makefiles to allow docker image cache usage based on env var
diff --git a/containers/synchronizer/Makefile b/containers/synchronizer/Makefile
index ebfe5ef..8620438 100644
--- a/containers/synchronizer/Makefile
+++ b/containers/synchronizer/Makefile
@@ -1,8 +1,9 @@
IMAGE_NAME:=xosproject/xos-synchronizer-openstack
CONTAINER_NAME:=xos-synchronizer
+NO_DOCKER_CACHE?=false
.PHONY: build
-build: ; docker build --rm -t ${IMAGE_NAME} .
+build: ; docker build --no-cache=${NO_DOCKER_CACHE} --rm -t ${IMAGE_NAME} .
.PHONY: run
run: ; docker run -d --name ${CONTAINER_NAME} ${IMAGE_NAME}