Updated to rebased core branch
Temporarily use the renamed but deprecated _url() function.
Implementation of Attachment endpoint. Initial work.
Implement field item normalization.
Start to implement head and get methods, add tests for these methods and normalizer.
Add _attachments key to normalized content entity, fix FileItemNormalizerTest.
Head and Get methods implementation, add more test cases.
Replace name with field_name for field_storage_config entity type.
Add response for the files that does not live on disk.
Add put and delete methods, work in progress.
Normalizer and resource fixes.
Uncomment commented test cases.
Call field normalize method once.
Rename the service for FileItemNormalizer.
Add Param Converter for file uuid, use file.mime_type.guesser service.
Use getMimeType() instead of mime type guesser.
Made the EntityUuidConverter work and implemented temporary route format and encoding support.
Implemented AttachmentNormalizer and StreamEncoder to deal with attachment functionality
Initial working version of the GET and HEAD methods for the attachment resource
Fixed the PUT method for the attachment resource. Plus some late night refactoring to make the resources leaner.