QPID-4698: Fixed the location of the SASL2 configuration file.

It was mistakenly installed to /etc/qpid/sasl2 rather than /etc/sasl2.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1477267 13f79535-47bb-0310-9956-ffa450edef68