Propagate Bookalope's error descriptions properly.
Propagate Bookalope's error descriptions properly.

When the Bookalope server encounters a problem, it returns a JSON string as the
response body, which contains the description of the error. Instead of ignoring
this string the wrapper now propagates it as part of the thrown exception.

jenstroeger/Bookalope,jenstroeger/Bookalope,jenstroeger/Bookalope