Add install to the makefile. Fix issue #1

Makefile

@@ -5,3 +5,19 @@ node-bench:
 	@! test -d build && mkdir build || true
 	@gcc -DNODE_BENCH="\"$(PWD)/lib/cli-wrapper.js\"" -o build/node-bench src/node-bench.c
 	@echo "built"
+
+install: node-bench
+	@cp build/node-bench /usr/local/bin/
+	@echo "installed"
+
+clean: uninstall
+	@[ -d build ] && rm -rf build || true
+	@echo "cleaned"
+
+uninstall:
+	@[ -f /usr/local/bin/node-bench ] && rm /usr/local/bin/node-bench || true
+	@echo "uninstalled"
+
+link: node-bench
+	@ln -s build/node-bench /usr/local/bin/
+	@echo "linked"