Expose 'get_x_openstack_request_id' method in all OpenStack clients api bindings

All Openstack API bindings mainly python is being used by many OpenStack core Services or any other third party applications. Each of the OpenStack Restful API returns X-Openstack-Request-Id in the API response but this request id is not available to the caller from the client. If you run command with —debug option, then only client displays the X-Openstack-Request-Id on the console. If there is any issue with the OS API and user wants to report this issue to the service provider, X-Openstack-Request-Id will come handy.

We are proposing to add get_x_openstack_request_id method in all OpenStack python API bindings.

Design:
When a caller make a call and get a response from the OpenStack service, it will extract
X-Openstack-Request-Id from the response header and store it in the thread local storage. Add a new method ‘get_x_openstack_request_id’ in the client to return X-Openstack-Request-Id stored in the thread local storage to the caller. We need to store request id in the TLS because same client object could be used in multithread application to interact with the OpenStack services.

Example
from cinderclient import client

cinder = client.Client('2', 'demo', 'admin', 'demo', 'http://21.12.4.342:5000/v2.0')

cinder.volumes.list()
[<Volume: 88c77848-ef8e-4d0a-9bbe-61ac41de0f0e>, <Volume: 4b731517-2f3d-4c93-a580-77665585f8ca>]

cinder.get_openstack_request_id()
'req-a9b74258-0b21-49c2-8ce8-673b420e20cc'

We will make changes to the following python api bindings:
1. python-cinderclient
2. python-novaclient
3. python-glanceclient
4. python-heatclient
5. python-neutronclient