v1.4.0

Added

• Add contribution guidelines -- currently we are unable to accept Pull Requests.
• Add --glossary-id argument for CLI document command.

Changed

• Improve README.
• Raise DocumentNotReadyException when attempting to download a document before it has been translated. Previously the
  base class DeepLException was thrown.

Fixed

• Add optional filename argument to translate_document_upload() to fix uploading file content as string or bytes.