PROTON-593: update paths in java send+recv example scripts

Applied patch from Marcel Meulemans

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1604198 13f79535-47bb-0310-9956-ffa450edef68
PROTON-613: send 'Hello World!' in the message if no alternative bodies are provided. Use the same initial address as other languages

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1604199 13f79535-47bb-0310-9956-ffa450edef68