Previously, only when an exception has a content with
{'NeutronError': {'type': xxxx, 'message': xxxx}},
exception per status code is raised from neutronclient library.
There are cases where this kind of message is not contained
in exception messages, for example, some extension is loaded.
Library users expect an exception is raised based on response
status code and it should not depend on an exception message.
This commit applies a fallback logic to map generic per-status
exception to all exception types from the neutron server.
Closes-Bug: #1513879
Change-Id: Ib3d0a8359aed444b12217b3404d40443d61fc2c0
af1a55bfd2