Refactor checksum code, and add Objectname hashing per uploaded objects

Add placeholder sha256, sha512 implementations from Intel with AVX, AVX2
and SSE4.1 extensions - with some boilerplate Go code.

Godeps/Godeps.json

@@ -1,6 +1,6 @@
 {
 	"ImportPath": "github.com/minio-io/minio",
-	"GoVersion": "go1.3.3",
+	"GoVersion": "go1.4",
 	"Packages": [
 		"./..."
 	],
@@ -18,6 +18,10 @@
 			"ImportPath": "github.com/gorilla/mux",
 			"Rev": "e444e69cbd2e2e3e0749a2f3c717cec491552bbf"
 		},
+		{
+			"ImportPath": "github.com/spaolacci/murmur3",
+			"Rev": "9d87265e0948d305ffe0383d54e59c3ac3482454"
+		},
 		{
 			"ImportPath": "github.com/tchap/go-patricia/patricia",
 			"Comment": "v1.0.1",