config: Migrate to the new version. Remove backend details.

Migrate to new config format v4.
```
{
	"version": "4",
	"credential": {
		"accessKey": "WLGDGYAQYIGI833EV05A",
		"secretKey": "BYvgJM101sHngl2uzjXS/OBF/aMxAN06JrJ3qJlF"
	},
	"region": "us-east-1",
	"logger": {
		"console": {
			"enable": true,
			"level": "fatal"
		},
		"file": {
			"enable": false,
			"fileName": "",
			"level": "error"
		},
		"syslog": {
			"enable": false,
			"address": "",
			"level": "debug"
		}
	}
}
```

This patch also updates [minio cli spec](./minio.md)

server_fs_test.go

@@ -81,15 +81,15 @@ func (s *MyAPISuite) SetUpSuite(c *C) {
 	// Initialize server config.
 	initConfig()
 
+	// Set port.
+	addr := ":" + strconv.Itoa(getFreePort())
+
 	// Get credential.
 	s.credential = serverConfig.GetCredential()
 
 	// Set a default region.
 	serverConfig.SetRegion("us-east-1")
 
-	// Set a new address.
-	serverConfig.SetAddr(":" + strconv.Itoa(getFreePort()))
-
 	// Do this only once here
 	setGlobalConfigPath(root)
 
@@ -99,8 +99,8 @@ func (s *MyAPISuite) SetUpSuite(c *C) {
 	fs, err := newFS(fsroot)
 	c.Assert(err, IsNil)
 
-	httpHandler := configureServerHandler(fs)
-	testAPIFSCacheServer = httptest.NewServer(httpHandler)
+	apiServer := configureServer(addr, fs)
+	testAPIFSCacheServer = httptest.NewServer(apiServer.Handler)
 }
 
 func (s *MyAPISuite) TearDownSuite(c *C) {