[WIP] 1.0 cleanup

TODO:

- [x] auto-determine region when using `s3://` style URL
- [ ] ~~specs for `box_add` extensions~~
- functional tests
  - [x] US standard simple (has non-standard endpoint)
  - [x] non US standard simple
  - [x] US standard simple 's3://' style
  - [x] non US standard simple 's3://' style
  - [x] S3 metadata
  - [ ] ~~local metadata~~
  - [x] specs for error messages?