Add status_code to RESTful exceptions

tempest.lib rest_client translates a error response to the
corresponding exception, but these exceptions don't have some
attribute which shows the original status code.
This patch adds that to them for re-using the original code
after exceptions happen.

Partially implements blueprint bug-notification-decorator

Change-Id: Icfa90a5e5f1991d9b1dbc781bd60850b5bcb041e
1 file changed