Update: add docker build target and integration test target

Author: relastle

Makefile

@@ -13,3 +13,11 @@ bench:
 .PHONY: lint
 lint:
 	golint ./main.go
+
+.PHONY: docker
+docker:
+	docker build -t relastle/pmy:0.1.0 -f docker/Dockerfile .
+
+.PHONY: integration_test
+integration_test:
+	(cd ./integration_test && go test -run .)