[DAS2] Content type for DAS XML responses

[Chervitz, Steve]

Currently, the DAS/2 spec dictates that responses should have content-types
like:

  application/x-das-source
  application/x-das-types
  application/x-das-region

Changing these to be 'text/xml' would be more convenient since the content
would then be viewable in a standard web browser. This would also be good
for backward compatibility with DAS/1 (where content-type is text/plain).

If we wanted, we could provide auxiliary information using attribute=value
notation:

  text/xml; dasformat=source
  text/xml; dasformat=types
  text/xml; dasformat=region

The corresponding compact content-types could be:

  text/plain; dasformat=compact-source
  text/plain; dasformat=compact-types
  text/plain; dasformat=compact-region

And other types could be:

  text/plain; dasformat=fasta
  text/plain; dasformat=gff3
  text/plain; dasformat=bed

Objections?

Steve

Refs: 
http://www.w3.org/TR/xhtml-media-types/#text-xml
http://www.iana.org/assignments/media-types/