DISPATCH-16: Fix default logging to stdout, broken in prevoius commit.

Other fixes
- Get rid of string literals.
- lowercase levels: consistent with qpidd and syslog.
- timestamp config working, better boolean configuration.

git-svn-id: https://svn.apache.org/repos/asf/qpid/dispatch/trunk@1596996 13f79535-47bb-0310-9956-ffa450edef68