MINOR: Add more JavaDoc (Plugin, Connection)
MINOR: JavaDoc for FixedChunker
MAJOR: Use HKDF from BouncyCastle to derive keys; MINOR: More JavaDoc for Indexer
MINOR: MOre JavaDoc (Fingerprinter, Adler32Fingerprinter, GzipTransformer, FileContent)
MINOR: Update S3 plugin to put multichunk files in data folder.