params.BackupsMetadataResult.UpdateFromMetadata -> apiserver/backups.ResultFromMetadata.
Merge pull request #1264 from ericsnowcurrently/backups-break-cycle

Drop an import-cycle-waiting-to-happen from apiserver/params.

Factor out the UpdateFromMetadata method of params.BackupsMetadataResult into apiserver/backups as ResultFromMetadata. This helps avoid the possibility of import cycles with anything backups imports since apiserver.params is imported in all sorts of places you wouldn't expect.

(Review request: http://reviews.vapour.ws/r/578/)
Add the backups Add method.
Add the API facade method for backups upload.
Add the API client method for backups upload.
Add BuildMetadata.
Add the backups upload subcommand.
Use an HTTP-based approach.
Add some logging around the API request handling.
Fix (and use) the chained reader.
Fix the upload API return value.
Add --quiet and --show-uploaded options.
Support "unknown" values for metadata origins.
Remove the "direct upload" facade method.
Fix an error message.
Empty out the ID and the stored timestamp.
Validate the incoming backup data.
Relax about doc.Stored and doc.Finished.
Drop the method arg.
Drop debug logging.