Implement scripts for perfoming basic file manupulation on Amazon S3.

s3 -- basic S3 functionality.  Implements the following commands:
  put: put a file onto S3
  get: copy a file from S3
  list: list the contents of an S3 bucket
  buckets: list buckets
  rm: remove a file from S3
  rmrf: remove all files from a bucket on S3

All commands follow the same format:
  s3 cmd bucket remote_name local_name (if different from remote_name)
You will need two environment variables set:
  S3_ACCESS_KEY_ID: your S3 access key id.
  S3_SECRET_ACCESS_KEY: the name of the file that contains your S3 secret key.

s3 only prints diagnostics if prerequisites are not met, 
so check the shell return codes.


hmac -- calculate an hmac.  Used by s3.
Call it like so:
  hmac hash keyfile file

The hash will be printed in binary form to stdout.  
If file is missing, hmac will hash whatever is input on stdin.


There are several things which are incomplete, missing, or flat-out wrong.
Send patches to [email protected] if you fix something!