normalize return keys for bulk delete and support > 10000 objects
When we ask to delete all objects, actually list them all
If the Response Status is not 200 and Errors is empty, add the Response Body to errors
A few missing get_metadata calls that need a prefix kwarg
Merge pull request #482 from sivel/more-get-meta-prefix

Add prefix kwarg to a few remaining get_metadata functions
session_persistence is a read/write property

Update docs pertaining to session_persistenence of CloudLoadBalancer to
indicate that it is now a read/write property. Fixes #485
Merge pull request #486 from sivel/lb-docs-sp-update

session_persistence is a read/write property
Add test for 413 to populate errors, when none are returned from the API
Merge pull request #480 from sivel/fix-bulk-upload

BulkDeleter: normalize return keys and support > 10000 objects