ROL-1870 Disallow creation of bookmarks of a name already in the folder while still allowing legacy duplicate bookmarks and duplicate bookmarks created by moving bookmarks from one folder to another.  Also, some Sonar fixes made.

git-svn-id: https://svn.apache.org/repos/asf/roller/trunk@1577406 13f79535-47bb-0310-9956-ffa450edef68