Fixes (temporarily) missing transaction manager problem when accessing the manifest via the rest api.  See durastore/src/main/webapp/WEB-INF/config/duracloud-app-config.xml for more detailed account of the problem.
ensures that empty logs return a 404 rather than 500 httpcode.
Fixes a minor problem in the AuditLogReaderImpl that was causing two spaces with similar paths to be displayed in the audit log.
Given spaces x and xy, when the user requested space x, they would get space x and xy. Problem was resolved by adding a '/' to the
end of the prefix argument.