OPENDJ-2343: minor usability improvements to backendstat tool Renamed sub-commands to use terminology which is more familiar to end- users: High-level sub-commands: * list-backends - lists pluggable backends * list-base-dns - lists base DNs of a pluggable backend * list-indexes - lists all indexes within a backend/baseDN * show-index-status - shows summary of attribute indexes within a backend/baseDN * dump-index - dumps an index and decodes key/values Low-level sub-commands: * list-raw-dbs - lists underlying databases within a backend * dump-raw-db - dumps raw hex content of a database. In addition, command line options have been updated to avoid terms like "storage", "tree", "entry container", and "root container".

OPENDJ-2343: rename backendtool to backendstat As agreed when reviewing the initial pull request for the tool.