Fixes#22
- In case of a HTTP error the PastedAccount method is supposed to return the HTTP response, since this can hold valuable information about the reason why the request failed. Instead, it was returning `nil`. This PR fixes this behaviour.
- Additionally, this PR introduces tests to catch such oversights
- Finally a proper `error.New()` error has been introduces, to that `error.Is()` can be used on common error that are detected by the module