ObjectStorage Retry Until Success Behavior

* Changed the retry_until_success behavior
  from an exponential backoff functionality
  to a max retries functionality. The method
  now takes a max_retries and sleep_time as
  optional parameters.

* Changed list_objects, list_containers, and
  get_object_count methods to match the new
  signature for retry_until_success.

* Added two variables, max_retry_count and
  retry_sleep_time, to be used for defaults
  for the retry_until_success method.

Change-Id: I96260166a97e6b621609502d07e891da23f45b2f
Merge "ObjectStorage Retry Until Success Behavior"