Refactor delayed response code.
Refactor delayed response code.

This patch introduces a record to better organize delayed response values
and removes some duplication around the actual start of the response.

BugzID: 12569

Conflicts:

	src/chttpd.erl

fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb