Change App Version Info Variable Names in Makefile

Since we have changed the App Info Variables in Commit
d777dd4 we have to change them also in
the Makefile under the `ldflags` or it would break the Makefile.

This is the last Patch which implements the Enhancement of #30

Why changing the App Info Variable Names?

Because goreleaser use those Names as from default so we have not to
edit more Fields of the `.goreleaser.yaml` Config.

Makefile

@@ -22,4 +22,4 @@ build:
 	git fetch --tags
 	@echo "++ Building kubenab go binary..."
 	mkdir -p bin
-	cd cmd/kubenab && go build $(STRIP_DEBUG) -a --installsuffix cgo --ldflags="-s -X main.AppVersion=$(APP_VERSION) -X main.BuildDate=$(BUILD_DATE) -X main.GitHash=$(GIT_HASH)" -o $(OUT_DIR)/kubenab
+	cd cmd/kubenab && go build $(STRIP_DEBUG) -a --installsuffix cgo --ldflags="-s -X main.version=$(APP_VERSION) -X main.date=$(BUILD_DATE) -X main.commit=$(GIT_HASH)" -o $(OUT_DIR)/kubenab