Media, JAXB Improvements & Small Improvements

Added: HardDrive is replaced by Media: The new media system supports
other drives (like network ones) and no longer limits to the hard drive.
Added: JAXB non-arg constructors are now protected so other classes
can't use them.
Added: Made small improvements, like adding an InfoString-interface for
toInfoString() or fixing comment issues from the last commits.