Merge pull request #5 from a4lg/robust-docker-detection

Detect Docker robustly

Makefile

@@ -41,7 +41,7 @@ all: build
 
 build: 
 	@echo "Checking if Docker is available..."
-	@if command -v docker &> /dev/null ; then \
+	@if command -v docker >/dev/null 2>&1 ; then \
 		echo "Docker is available, building inside Docker container..."; \
 		$(MAKE) build-container; \
 	else \