[Delivers #50230813] Add Support for Bulk Delete

### Changes
- Added a bulk delete method to the Rackspace `CloudFilesProvider` class.  This takes in a list of containers and/or objects to be deleted.  Can support 10,000 objects simultaneously.  
- Added a __deleteObjects__ flag to the __DeleteContainer__ method.  When true, all files are retrieved and then deleted via bulk delete method before deleting the container.
- Modified the __DeleteObject__ method to use the bulk delete when deleting the file segments.