deps: update images to v0.18.0

Update the images dependency to v0.18.0
This includes a change in the Fedora IoT remote configuration which is
now installed through an RPM instead of being hard-coded in the image
definitions.

vendor/github.com/distribution/reference/Makefile

@@ -0,0 +1,25 @@
+# Project packages.
+PACKAGES=$(shell go list ./...)
+
+# Flags passed to `go test`
+BUILDFLAGS ?= 
+TESTFLAGS ?= 
+
+.PHONY: all build test coverage
+.DEFAULT: all
+
+all: build
+
+build: ## no binaries to build, so just check compilation suceeds
+	go build ${BUILDFLAGS} ./...
+
+test: ## run tests
+	go test ${TESTFLAGS} ./...
+
+coverage: ## generate coverprofiles from the unit tests
+	rm -f coverage.txt
+	go test ${TESTFLAGS} -cover -coverprofile=cover.out ./...
+
+.PHONY: help
+help:
+	@awk 'BEGIN {FS = ":.*##"; printf "\nUsage:\n  make \033[36m\033[0m\n"} /^[a-zA-Z_\/%-]+:.*?##/ { printf "  \033[36m%-27s\033[0m %s\n", $$1, $$2 } /^##@/ { printf "\n\033[1m%s\033[0m\n", substr($$0, 5) } ' $(MAKEFILE_LIST)