add a makefile (#11)

I like the makefile since it hides a lot of the tooling options.

Makefile

@@ -0,0 +1,34 @@
+SOURCE_DIRS      = cmd
+SOURCES          := $(shell find . -name '*.go' -not -path "*/vendor/*")
+.DEFAULT_GOAL    := sbcli
+
+sbcli: $(SOURCES) ## Build the samplebroker
+	go build -i -ldflags="-s -w"
+
+lint: ## Run golint
+	@golint -set_exit_status $(addsuffix /... , $(SOURCE_DIRS))
+
+fmtcheck: ## Check go formatting
+	@gofmt -l $(SOURCES) | grep ".*\.go"; if [ "$$?" = "0" ]; then exit 1; fi
+
+test: ## Run unit tests
+	@go test -cover ./cmd/...
+
+vet: ## Run go vet
+	@go tool vet ./cmd
+
+check: fmtcheck vet lint sbcli test ## Pre-flight checks before creating PR
+
+clean: ## Clean up your working environment
+	@rm -f sbcli
+
+help: ## Show this help screen
+	@echo 'Usage: make <OPTIONS> ... <TARGETS>'
+	@echo ''
+	@echo 'Available targets are:'
+	@echo ''
+	@grep -E '^[ a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | \
+		awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-20s\033[0m %s\n", $$1, $$2}'
+	@echo ''
+
+.PHONY: clean lint build fmtcheck test vet help