fix makefile installs

Author: whyrusleeping

sharness/Makefile

@@ -67,7 +67,7 @@ bin/ipfs-update: $(call find_go_files, $(IPFS_UPDATE_SRC)) BUILD-OPTIONS
 
 bin/random-files:
 	@echo "*** installing $@ ***"
-	go get github.com/jbenet/go-random-files
+	go get github.com/jbenet/go-random-files/random-files
 	go build $(GOFLAGS) -o $@ github.com/jbenet/go-random-files/random-files
 
 bin/go-sleep: