Bug fix for encrypted files, speeds up, and new features

- Limited backup retrieval to the first snapshot, and the last 2. iCloud only ever holds a total of 3 backups worth of data.

- Re-wrote the list_files() function to grab more than 100 at a time. There does not appear to be an actual limit, and multiple requests dramatically slows down retrieval.

- Added a new command option, "--combine", which combines all 3 downloaded snapshots into a single snapshot. Useful if all you really want is the most current set of data.

- Added a new command option, "--itunes_style" which attempts to create an iTunes-style backup, which can then be read by 3rd party forensic tools. Can be combined with the option.