v5.0.6

• IIIF information endpoints always return JSON in HTTP 4xx responses.
• Fixed a bug whereby the values of the operations and page_count keys
  in the delegate context were not set.
• TurboJpegProcessor is able to generate non-JPEG derivative images, which
  fixes an HTTP 415 error that would occur when trying to do that.
• Fixed a crop-offset bug that could occur when using PdfBoxProcessor to
  generate JPEGs with libjpeg-turbo active.
• Updating libraries to fix security issues. Full details in #634
• Update of Jena to 4.8 requires RDF to have a populated rdf:about field. May impact some XMP header processing.