Adds requirements.txt for test requirements
Adds statsd support/bug fixes

SFTP: Adds statsd support.
FTP: Adds statsd support.
FTP: BUG FIX: An 'access' command will now return correct response on a non-existing container.
SFTP: BUG FIX: Deleting a non-existing object-directory will return a success.
Swift Client: Re-authenticates and retries request when there's a 401 failure.
              This is intended to avoid problems from expiring auth tokens.
Switches Most Stats to use Guage.