Registrations for existing patch media types

[awwright]

By registering existing file formats with a media type, they would become available for use as a PATCH body.

Candidates include:

• VCDIFF: RFC 3284 (IETF)
• diff -e format: POSIX (The Open Group/IEEE)

See also HTTP Delta Encoding: RFC 3229 (Individual submission) which assigns identifiers to various patch formats.