Refactor proxies section

I learned how to Makefile

Makefile

@@ -18,26 +18,29 @@ endif
 build: clean gofmt lint
 	$(ENVVAR) go build -o kube-monkey
 
-# Supressing docker build avoids printing the env variables
-container: test
+proxies:
 ifneq ($(and $(http_proxy), $(https_proxy)),)
 	@echo Starting Docker build, importing both http_proxy and https_proxy env variables
-	@docker build --build-arg http_proxy=$(http_proxy) --build-arg https_proxy=$(https_proxy) -t kube-monkey:$(TAG) .
+dockerbuild=docker build --build-arg http_proxy=$(http_proxy) --build-arg https_proxy=$(https_proxy)
 else
 ifdef http_proxy
 	@echo Starting Docker build, importing http_proxy
-	@docker build --build-arg http_proxy=$(http_proxy) -t kube-monkey:$(TAG) .
+dockerbuild= docker build --build-arg http_proxy=$(http_proxy)
 else
 ifdef https_proxy
 	@echo Starting Docker build, importing https_proxy
-	@docker build --build-arg https_proxy=$(https_proxy) -t kube-monkey:$(TAG) .
+dockerbuild= docker build --build-arg https_proxy=$(https_proxy)
 else
 	@echo no env proxies set, building normally
-	docker build -t kube-monkey:$(TAG) .
+dockerbuild= docker build -t kube-monkey:$(TAG) .
 endif
 endif
 endif
 
+# Supressing docker build avoids printing the env variables
+container: proxies test
+	@$(dockerbuild) -t kube-monkey:$(TAG) .
+
 gofmt:
 	find . -path ./vendor -prune -o -name '*.go' -print | xargs -L 1 -I % gofmt -s -w %