PROTON-513: use the correct encoding for ulong values over 2^63-1

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1566142 13f79535-47bb-0310-9956-ffa450edef68
PROTON-514: use the correct encoding for uint values over 2^31-1

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1566143 13f79535-47bb-0310-9956-ffa450edef68