Make get/put more robust

- init folder if not present already in 'get()' call
  - put.go was referencing wrong args - fix it
  - if no OBJECTNAME is specified during 'get' - grab a
    list of files under "~/.minio"
  - Provide new API GetList() for ObjectStorage struct

pkgs/storage/fsstorage/fs_storage.go

@@ -11,12 +11,27 @@ type FileSystemStorage struct {
 	RootDir string
 }
 
+func (storage FileSystemStorage) GetList() ([]byte, error) {
+	fileInfos, err := ioutil.ReadDir(storage.RootDir)
+	if err != nil {
+		return nil, err
+	}
+
+	var list []byte
+	for _, fi := range fileInfos {
+		list = append(list, "{"+fi.Name()+"}\n"...)
+	}
+	return list, nil
+}
+
 func (storage FileSystemStorage) Get(objectPath string) ([]byte, error) {
 	return ioutil.ReadFile(path.Join(storage.RootDir, objectPath))
-
 }
 
 func (storage FileSystemStorage) Put(objectPath string, object []byte) error {
-	os.MkdirAll(filepath.Dir(path.Join(storage.RootDir, objectPath)), 0700)
+	err := os.MkdirAll(filepath.Dir(path.Join(storage.RootDir, objectPath)), 0700)
+	if err != nil {
+		return err
+	}
 	return ioutil.WriteFile(path.Join(storage.RootDir, objectPath), object, 0600)
 }

pkgs/storage/storage.go

@@ -1,6 +1,7 @@
 package storage
 
 type ObjectStorage interface {
+	GetList() ([]byte, error)
 	Get(path string) ([]byte, error)
 	Put(path string, object []byte) error
 }