When reading attachments, avoid closing connections too early
When reading attachments, avoid closing connections too early

Signal mochiweb to not send connection:close headers
in order for the socket to be reused.

Before this commit, this signaling was done too late.

COUCHDB-2834

fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,apache/couchdb-couch,apache/couchdb-couch,fkaempfer/couchdb,cloudant/couchdb-couch,apache/couchdb-couch,fkaempfer/couchdb,cloudant/couchdb-couch,cloudant/couchdb-couch,fkaempfer/couchdb