Libcoveweb2

When upgrading to this version, `ALLOWED_UNKNOWN_CONTENT_TYPES` must be set in the Django settings file, ideally from the settings file included with this library.

Added

- base.html: Wrap default terms and conditions in template block so it can be overridden
- utils.py: get_file_type_for_flatten_tool: consider content type too
- settings.ALLOWED_UNKNOWN_CONTENT_TYPES.

Fixed

- utils.py: get_file_type_for_flatten_tool: include an error message in raise at end https://github.com/OpenDataServices/lib-cove-web-2/issues/3

Added

- Model SuppliedDataFile has new method storage_name for use with Django storage (like storage_dir on SuppliedData)

First Release