Okdata-aws

* Fix bug in validator `ensure_format_of_error`.

* The field `errors` has been added to `StatusData`.

* The `okdata` namespace package now uses the old-style `pkg_resources`
declaration instead of being an implicit namespace package.

* The status wrapper no longer throws an exception when receiving an HTTP error
response from the status API, but logs it instead.

* Added `status_wrapper` and `status_add` from common-python under
`okdata.aws.status`.

* Initial release based on the old `common-python` project.