+ Optimized Download

+ Implemented a more optimized version of Download.
+ Once again , a hash map keeps tracks of the last_modified time of the
files in the bucket
+ the files are downloaded only in case the files have changed since
the last time it was downloaded (or if new files have been added)
+ Cleaned some up some ( removed the code that was commented out)
+ Removed import pip line ! Grrr !