func (b *Bucket) GetReader(path string, c *Config) (r io.ReadCloser, h http.Header, err error) {
	if path == "" {
		return nil, nil, errors.New("empty path requested")
	}
	if c == nil {
		c = b.conf()
	}
	u, err := b.url(path, c)
	if err != nil {
		return nil, nil, err
	}
	return newGetter(*u, c, b)
}
func (b *Bucket) GetReader(path string, c *Config) (r io.ReadCloser, h http.Header, err error) {
	if path == "" {
		return nil, nil, errors.New("empty path requested")
	}
	if c == nil {
		c = b.conf()
	}
	u, err := b.url(path, c)
	if err != nil {
		return nil, nil, err
	}
	return newGetter(*u, c, b)
}
// GetReader provides a reader and downloads data using parallel ranged get requests.
// Data from the requests are ordered and written sequentially.
//
// Data integrity is verified via the option specified in c.
// Header data from the downloaded object is also returned, useful for reading object metadata.
// DefaultConfig is used if c is nil
// Callers should call Close on r to ensure that all resources are released.
//
// To specify an object version in a versioned bucket, the version ID may be included in the path as a url parameter. See http://docs.aws.amazon.com/AmazonS3/latest/dev/RetrievingObjectVersions.html