Feature request: Return the error code when there's an HTTP error

[XSchelin]

I'm running a backup script I wrote to get attachments out of LastPass, and I started getting:

Error: HTTP response code said error.

I enabled logging per #228 and saw that I was getting rate limited (429 error code).

Feature request: When there's an HTTP response code saying error, return what the error is, so that we're not hunting the internet for what the problem actually is.