[kitten] Service discovery URI field case-sensitivity

[Matt Rogers <[e-mail]>]

The service discovery draft needs some clarification of the encoding
and case sensitivity for the URI field values, and I have heard some
different views on how they should be defined. 

First I believe the scheme should be case-insensitive per BCP 35 advice
on URI scheme values. 

Flags, if specified as case-sensitive would allow more flag values at
the expense of some possible operator confusion (however, the values
will be IANA registered and a valid character range specified).
Transport type values will also be IANA registered and case-sensitivity 
would not gain us anything here. These fields are currently case-
insensitive in the MIT krb5 implementation.

Transport info field can have both case-sensitive and case-insensitive
elements as defined by the transport, like the KKDCP path and hostname.
MIT krb5 treats KKDCP URLs in this respect.

Overall my preference would be to define in their respective sections,
the scheme, flags, and transport-type fields as case-insensitive and
say the transport-info field's case rules are to determined by the
transport specification.  Although this limits the flags, If we really
ran out of flags in the future then the document could be updated.

Regards,
Matt