Square-file-store

- rearrange file structure.
- add versions to all api endpoints.
- standard output for json outputs.
- replace hardcoded column names with variables from square_database_structure.
- update tests.
- refactor some code logic.

**Full Changelog**: https://github.com/thepmsquare/square_file_store/compare/1.0.1...2.0.0

- replace file_purpose with app_id.

**Full Changelog**: https://github.com/thepmsquare/square_file_store/compare/1.0.0...1.0.1