neutron fails with BadRequest

[Choe, Cheng-Dae]

when neutron api failed. openstack sdk reports just "HttpException: BadRequest".

in debug mode says that openstack receive error message in body as key "NeutronError"

RESP BODY: {"NeutronError": {"message": "Invalid input for routes. Reason: Duplicate hostroute '{u'nexthop': u'10.51.68.25', u'destination': u'10.10.10.0/24'}'.", "type": "HTTPBadRequest", "detail": ""}}

and python-neutronclient handles this message in https://github.com/openstack/python-neutronclient/blob/master/neutronclient/v2_0/client.py#L46

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/386440
Committed: https://git.openstack.org/cgit/openstack/python-openstacksdk/commit/?id=23f4aa883244098f121c244e897c417410a8544f
Submitter: Jenkins
Branch: master

commit 23f4aa883244098f121c244e897c417410a8544f
Author: Choe, Cheng-Dae <email address hidden>
Date: Fri Oct 14 16:55:45 2016 +0900

    Display neutron api error message more precisely

    When neutron-api response fails. Session object reports error as

        HttpException: Bad Request

    and this cause lack of error information on openstack cli output.
    buy the way neutron failure response body contains more informations

        {"NeutronError": {
     "message": "here is error message", "type": "HTTPBadRequest",
     "detail": ""}}

    This changes raise exception with more precise error messages.

    Change-Id: Ibea40e37ee6b6135f8b00c8a46e023ff59befd5b
    Closes-Bug: 1633361