1. Add a buffer to osrfAppSession structure; for future use

1. Add a buffer to osrfAppSession structure; for future use

2. New function osrfSendTransportPayload().  This a repackaging of
existing functionality pulled out into a separate function so that
it can be reused in other contexts.

These changes are preparation for future changes, and will have no
visible effect by themselves.

M    include/opensrf/osrf_app_session.h
M    src/libopensrf/osrf_app_session.c

git-svn-id: svn://svn.open-ils.org/OpenSRF/trunk@1986 9efc2488-bf62-4759-914b-345cdb29e865