QPID-5138: Rename PreferencesServlet into LoggedOnUserPreferencesServlet

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1529363 13f79535-47bb-0310-9956-ffa450edef68
QPID-5138: Move logout link into user drop-down menu

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1529364 13f79535-47bb-0310-9956-ffa450edef68