Add details to stdout error message.

Current glance command does not show the details of error message.
For example, the glance command shows HTTPBadRequest only if some
necessary parameter is not specified.

 $ glance image-create --file root-fs.img --name cirros-0.3.0-x86_64-uec
 Request returned failure status.
 HTTPBadRequest (HTTP 400)
 $

By only the above message, it is not easy that a user understand the reason
of an error. glance-api server returns the details of reason, but glance
command does not show it.

This patch adds details, which is gotten from glance-api server, to error
message. And a user will be able to understand the reason of a error like
the following:

 $ glance image-create --file root-fs.img --name cirros-0.3.0-x86_64-uec
 Request returned failure status.
 400 Bad Request
 Invalid disk format 'None' for image.
     (HTTP 400)
 $

Fixes bug 1094917

Change-Id: I49192c3ebbc8a70b63dcfcede9fd13f1688388cf