NO-JIRA: Fix tools/setup.py, was not respecting install prefix.

- Was installing into absolute /usr directories, changed to install relative to prefix.
- Was installing to non-standard "/usr/shared" directory, changed to Unix standard "<prefix>/share"

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1605637 13f79535-47bb-0310-9956-ffa450edef68