Add Abyss::Server::Session::readRequestBody(), change Abyss::Server::Session::writeResponseBody()

git-svn-id: http://svn.code.sf.net/p/xmlrpc-c/code@2634 98333e67-4a24-44d7-a75c-e53540dd3050
Encapsulate AbyssServer internals

git-svn-id: http://svn.code.sf.net/p/xmlrpc-c/code@2635 98333e67-4a24-44d7-a75c-e53540dd3050