Finished adding doxygen-style comments to document the app session

Finished adding doxygen-style comments to document the app session
functions.  Removed comments from the header so that they wouldn't
override more complete comments in the implementation file.

Tweaked the white space here and there.

Changed the return code in a few cases, for consistency.  A couple of
functions seemed unable to decide whether 0 was good and 1 was bad,
or vice versa.

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

git-svn-id: svn://svn.open-ils.org/OpenSRF/trunk@1883 9efc2488-bf62-4759-914b-345cdb29e865