Libcovebods

Changed

- Update to latest lib-cove and lib-cove-web, and make some changes to the tests for compatibility with these

Changed

- Update to latest lib-cove and lib-cove-web, and make some changes for compatibility with these

Fixed

- Catch error when `statementDate` is `null`

Changed

- Rename schema object attributes to remove word "release", as in latest lib-cove

Changed

- requirements: Update Django to 2.2 LTS and lib-cove to latest

Changes to packaging only;

- Removed all requirements files and moved to setup.py
- Require latest version of lib-cove, so that optional flatten-tool dependencies are pulled in [54](https://github.com/openownership/lib-cove-bods/pull/54#issuecomment-585303356)
- Moved data underneath main folder where it can be included in package