googlesheets v0.2.1

• XML is no longer a dependency.
• Automatic retries for Internal Server Error (HTTP 500). On or around 2016-03-11, there was a huge increase in the frequency of this error on Google Drive API calls.
  • Remedy: all HTTP GET calls in the package are automatically retried up to 5 times, with exponential backoff, for statuses 500 and higher.
• Functions prefixed with gd_ refer to Google Drive and might eventually migrate into a separate Google Drive package. Generally there is a synonym with the gs_ prefix.
• gd_token() is a new function to expose information about the current Google token. Some of this was migrated out of gd_user() and into gd_token(). New information includes scopes and cache path.
• gd_user() now returns an S3 object of class drive_user, but it's really just a list with a nice print method. It exposes information about the current Google user. New information includes user's Drive permissionId and rootFolderId.