Merge pull request #2658 from gdicristofaro/8271-removeVisitorCode

.../java/src/org/sleuthkit/datamodel/BlackboardArtifact.java

bindings/java/src/org/sleuthkit/datamodel/Content.java

...ings/java/src/org/sleuthkit/datamodel/ContentVisitor.java

bindings/java/src/org/sleuthkit/datamodel/DerivedFile.java

bindings/java/src/org/sleuthkit/datamodel/Directory.java

bindings/java/src/org/sleuthkit/datamodel/File.java

bindings/java/src/org/sleuthkit/datamodel/FileSystem.java

bindings/java/src/org/sleuthkit/datamodel/HostAddress.java

bindings/java/src/org/sleuthkit/datamodel/Image.java

bindings/java/src/org/sleuthkit/datamodel/LayoutFile.java

...ings/java/src/org/sleuthkit/datamodel/LocalDirectory.java

bindings/java/src/org/sleuthkit/datamodel/LocalFile.java

...ava/src/org/sleuthkit/datamodel/LocalFilesDataSource.java

bindings/java/src/org/sleuthkit/datamodel/OsAccount.java

bindings/java/src/org/sleuthkit/datamodel/Pool.java

bindings/java/src/org/sleuthkit/datamodel/Report.java

bindings/java/src/org/sleuthkit/datamodel/SlackFile.java

...ava/src/org/sleuthkit/datamodel/SleuthkitItemVisitor.java

...a/src/org/sleuthkit/datamodel/SleuthkitVisitableItem.java

.../java/src/org/sleuthkit/datamodel/UnsupportedContent.java