--------------------
Added
^^^^^
- Add writing of admin_metadata as content of admin_metadata_key
- Added ``storage_broker_version`` to structure parameters
- Added inheritance from ``dtoolcore.storagebroker.BaseStorageClass``
- Overrode ``get_text`` method on ``BaseStorageBroker`` class
- Overrode ``put_text`` method on ``BaseStorageBroker`` class
- Overrode ``get_admin_metadata_key`` method on ``BaseStorageBroker`` class
- Overrode ``get_readme_key`` method on ``BaseStorageBroker`` class
- Overrode ``get_manifest_key`` method on ``BaseStorageBroker`` class
- Overrode ``get_overlay_key`` method on ``BaseStorageBroker`` class
- Overrode ``get_structure_key`` method on ``BaseStorageBroker`` class
- Overrode ``get_dtool_readme_key`` method on ``BaseStorageBroker`` class
- Overrode ``get_size_in_bytes`` method on ``BaseStorageBroker`` class
- Overrode ``get_utc_timestamp`` method on ``BaseStorageBroker`` class
- Overrode ``get_hash`` method on ``BaseStorageBroker`` class