As part of some future-looking work on our JavaScript codebase, we need

a way to wrap errors from Backbone in a single object. Most backbone

error callbacks take three arguments: the object that encountered the

error (either a Model or Collection instance), the request (a

jQuery.XHR), and the options object that was passed into the call that

generated the error. This new error subclass wraps all of that up

together, setting the default message on the error to be the errorText

from the XHR object.

Used this in conjunction with other changes.