refactor ObjectLayer PutObject and PutObjectPart (#4925)

This change refactor the ObjectLayer PutObject and PutObjectPart
functions. Instead of passing an io.Reader and a size to PUT operations
ObejectLayer expects an HashReader.
A HashReader verifies the MD5 sum (and SHA256 sum if required) of the object.
This change updates all all PutObject(Part) calls and removes unnecessary code
in all ObjectLayer implementations.

Fixes #4923

cmd/object-api-utils_test.go

@@ -17,8 +17,6 @@
 package cmd
 
 import (
-	"io/ioutil"
-	"strings"
 	"testing"
 )
 
@@ -131,34 +129,6 @@ func TestIsValidObjectName(t *testing.T) {
 	}
 }
 
-// Tests rangeReader.
-func TestRangeReader(t *testing.T) {
-	testCases := []struct {
-		data   string
-		minLen int64
-		maxLen int64
-		err    error
-	}{
-		{"1234567890", 0, 15, nil},
-		{"1234567890", 0, 10, nil},
-		{"1234567890", 0, 5, toObjectErr(errDataTooLarge, "test", "test")},
-		{"123", 5, 10, toObjectErr(errDataTooSmall, "test", "test")},
-		{"123", 2, 10, nil},
-	}
-
-	for i, test := range testCases {
-		r := strings.NewReader(test.data)
-		_, err := ioutil.ReadAll(&rangeReader{
-			Reader: r,
-			Min:    test.minLen,
-			Max:    test.maxLen,
-		})
-		if toObjectErr(err, "test", "test") != test.err {
-			t.Fatalf("test %d failed: expected %v, got %v", i+1, test.err, err)
-		}
-	}
-}
-
 // Tests getCompleteMultipartMD5
 func TestGetCompleteMultipartMD5(t *testing.T) {
 	testCases := []struct {