HostBridge uses now a DataMover

The extraction of the data movement allows to implement different
strategies that can be applied on the data moved, like compression.
Merge branch 'master' of https://github.com/groggi/eth-jcd
Fixed implementation error of int read() in VDiskFileInputStream
Modified test to check for correct return value
JavaDoc fixes in DefaultMover
Implemented GZIP compressed mover
HostBridgeTest tests now DefaultMover and GZIPMover too
BigImportExportTest interface change fix
fixed EOS (return -1) bug also for all other read() methods
Movers now take care of closing the streams
Implemented EncryptedMover which encrypts files before writing onto virtual disk