directory structure change to work with glide

glide has its own requirements. My previous workaround caused me some
code checkin errors. Need to fix this.

weed/operation/compress.go

@@ -0,0 +1,59 @@
+package operation
+
+import (
+	"bytes"
+	"compress/flate"
+	"compress/gzip"
+	"io/ioutil"
+	"strings"
+
+	"github.com/chrislusf/seaweedfs/weed/glog"
+)
+
+/*
+* Default more not to gzip since gzip can be done on client side.
+ */
+func IsGzippable(ext, mtype string) bool {
+	if strings.HasPrefix(mtype, "text/") {
+		return true
+	}
+	switch ext {
+	case ".zip", ".rar", ".gz", ".bz2", ".xz":
+		return false
+	case ".pdf", ".txt", ".html", ".htm", ".css", ".js", ".json":
+		return true
+	}
+	if strings.HasPrefix(mtype, "application/") {
+		if strings.HasSuffix(mtype, "xml") {
+			return true
+		}
+		if strings.HasSuffix(mtype, "script") {
+			return true
+		}
+	}
+	return false
+}
+
+func GzipData(input []byte) ([]byte, error) {
+	buf := new(bytes.Buffer)
+	w, _ := gzip.NewWriterLevel(buf, flate.BestCompression)
+	if _, err := w.Write(input); err != nil {
+		glog.V(2).Infoln("error compressing data:", err)
+		return nil, err
+	}
+	if err := w.Close(); err != nil {
+		glog.V(2).Infoln("error closing compressed data:", err)
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}
+func UnGzipData(input []byte) ([]byte, error) {
+	buf := bytes.NewBuffer(input)
+	r, _ := gzip.NewReader(buf)
+	defer r.Close()
+	output, err := ioutil.ReadAll(r)
+	if err != nil {
+		glog.V(2).Infoln("error uncompressing data:", err)
+	}
+	return output, err
+}