Full restructure in accordance with

- pkg/{subsystem}/{package} style
  - modify Makefile to reflect the new style,
    consolidate various entries
  - add a dummy ``main.go`` at top level

pkg/storage/erasure/Makefile

@@ -0,0 +1,19 @@
+all: build test
+.PHONY: all
+
+SYSTEM_NAME := $(shell uname -s)
+
+test:
+	@godep go test -race -coverprofile=cover.out
+
+isal/isal-l.a:
+ifeq ($(SYSTEM_NAME), Darwin)
+	@$(MAKE) -C isal arch=osx lib
+else
+	@$(MAKE) -C isal lib
+endif
+build: isal/isal-l.a
+	@godep go build
+
+clean:
+	@rm -v cover.out