config/main: Re-write config files - add to new config v3

- New config format.

```
{
	"version": "3",
	"address": ":9000",
    "backend": {
          "type": "fs",
          "disk": "/path"
    },
	"credential": {
		"accessKey": "WLGDGYAQYIGI833EV05A",
		"secretKey": "BYvgJM101sHngl2uzjXS/OBF/aMxAN06JrJ3qJlF"
	},
	"region": "us-east-1",
	"logger": {
		"file": {
			"enable": false,
			"fileName": "",
			"level": "error"
		},
		"syslog": {
			"enable": false,
			"address": "",
			"level": "debug"
		},
		"console": {
			"enable": true,
			"level": "fatal"
		}
	}
}
```

New command lines in lieu of supporting XL.

Minio initialize filesystem backend.
~~~
$ minio init fs <path>
~~~

Minio initialize XL backend.
~~~
$ minio init xl <url1>...<url16>
~~~

For 'fs' backend it starts the server.
~~~
$ minio server
~~~

For 'xl' backend it waits for servers to join.
~~~
$ minio server
... [PROGRESS BAR] of servers connecting
~~~

Now on other servers execute 'join' and they connect.
~~~
....
minio join <url1> -- from <url2> && minio server
minio join <url1> -- from <url3> && minio server
...
...
minio join <url1> -- from <url16> && minio server
~~~

logger.go

@@ -1,5 +1,5 @@
 /*
- * Minio Cloud Storage, (C) 2015 Minio, Inc.
+ * Minio Cloud Storage, (C) 2015, 2016 Minio, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -28,6 +28,21 @@ type fields map[string]interface{}
 
 var log = logrus.New() // Default console logger.
 
+// logger carries logging configuration for various supported loggers.
+// Currently supported loggers are
+//
+//   - console [default]
+//   - file
+//   - syslog
+//
+type logger struct {
+	Console consoleLogger `json:"console"`
+	File    fileLogger    `json:"file"`
+	Syslog  syslogLogger  `json:"syslog"`
+	// Add new loggers here.
+}
+
+// errorIf synonymous with fatalIf but doesn't exit on error != nil
 func errorIf(err *probe.Error, msg string, fields map[string]interface{}) {
 	if err == nil {
 		return
@@ -49,6 +64,7 @@ func errorIf(err *probe.Error, msg string, fields map[string]interface{}) {
 	log.WithFields(fields).Error(msg)
 }
 
+// fatalIf wrapper function which takes error and prints jsonic error messages.
 func fatalIf(err *probe.Error, msg string, fields map[string]interface{}) {
 	if err == nil {
 		return