Rename GetBlob to just Blob

After having another look, this seemed more consistent with other method
names used in this package.

repositories.go

@@ -81,12 +81,12 @@ func (s *RepositoriesService) ListTree(pid interface{}, opt *ListTreeOptions, op
 	return t, resp, err
 }
 
-// GetBlob gets information about blob in repository like size and content.
-// Note that blob content is Base64 encoded.
+// Blob gets information about blob in repository like size and content. Note
+// that blob content is Base64 encoded.
 //
 // GitLab API docs:
 // https://docs.gitlab.com/ce/api/repositories.html#get-a-blob-from-repository
-func (s *RepositoriesService) GetBlob(pid interface{}, sha string, options ...OptionFunc) ([]byte, *Response, error) {
+func (s *RepositoriesService) Blob(pid interface{}, sha string, options ...OptionFunc) ([]byte, *Response, error) {
 	project, err := parseID(pid)
 	if err != nil {
 		return nil, nil, err