compliance: be compliant with dist-spec compliance tests

dist-spec compliance tests are now becoming a part of dist-spec repo
itself - we want to be compliant

pkg/api/regex.go:
	* revert uppercasing in repository names

pkg/api/routes.go:
	* ListTags() should support the URL params 'n' and 'last'
	  for pagination

	* s/uuid/session_id/g to use the dist-spec's naming

	* Fix off-by-one error in GetBlobUpload()'s http response "Range" header

	* DeleteManifest() success status code is 202

	* Fix PatchBlobUpload() to account for "streamed" use case
	  where neither "Content-Length" nor "Content-Range" headers are set

pkg/storage/storage.go:
	* Add a "streamed" version of PutBlobChunk() called PutBlobChunkStreamed()

pkg/compliance/v1_0_0/check.go:
	* fix unit tests to account for changed response status codes

pkg/storage/storage.go

@@ -243,6 +243,11 @@ func (is *ImageStore) GetImageManifest(repo string, reference string) ([]byte, s
 
 	if err != nil {
 		is.log.Error().Err(err).Str("dir", dir).Msg("failed to read index.json")
+
+		if os.IsNotExist(err) {
+			return nil, "", "", errors.ErrRepoNotFound
+		}
+
 		return nil, "", "", err
 	}
 
@@ -286,8 +291,14 @@ func (is *ImageStore) GetImageManifest(repo string, reference string) ([]byte, s
 	p = path.Join(p, digest.Encoded())
 
 	buf, err = ioutil.ReadFile(p)
+
 	if err != nil {
 		is.log.Error().Err(err).Str("blob", p).Msg("failed to read manifest")
+
+		if os.IsNotExist(err) {
+			return nil, "", "", errors.ErrManifestNotFound
+		}
+
 		return nil, "", "", err
 	}
 
@@ -548,6 +559,39 @@ func (is *ImageStore) GetBlobUpload(repo string, uuid string) (int64, error) {
 	return fi.Size(), nil
 }
 
+// PutBlobChunkStreamed appends another chunk of data to the specified blob. It returns
+// the number of actual bytes to the blob.
+func (is *ImageStore) PutBlobChunkStreamed(repo string, uuid string, body io.Reader) (int64, error) {
+	if err := is.InitRepo(repo); err != nil {
+		return -1, err
+	}
+
+	blobUploadPath := is.BlobUploadPath(repo, uuid)
+
+	_, err := os.Stat(blobUploadPath)
+	if err != nil {
+		return -1, errors.ErrUploadNotFound
+	}
+
+	file, err := os.OpenFile(
+		blobUploadPath,
+		os.O_WRONLY|os.O_CREATE,
+		0600,
+	)
+	if err != nil {
+		is.log.Fatal().Err(err).Msg("failed to open file")
+	}
+	defer file.Close()
+
+	if _, err := file.Seek(0, io.SeekEnd); err != nil {
+		is.log.Fatal().Err(err).Msg("failed to seek file")
+	}
+
+	n, err := io.Copy(file, body)
+
+	return n, err
+}
+
 // PutBlobChunk writes another chunk of data to the specified blob. It returns
 // the number of actual bytes to the blob.
 func (is *ImageStore) PutBlobChunk(repo string, uuid string, from int64, to int64,
@@ -579,7 +623,7 @@ func (is *ImageStore) PutBlobChunk(repo string, uuid string, from int64, to int6
 	}
 	defer file.Close()
 
-	if _, err := file.Seek(from, 0); err != nil {
+	if _, err := file.Seek(from, io.SeekStart); err != nil {
 		is.log.Fatal().Err(err).Msg("failed to seek file")
 	}