Return request-id in API response

Import RequestIdMiddleware from oslo which ensures to request-id
in API response. CatchErrorsMiddleware is also imported to ensure
all internal exceptions are caught outermost.
api-paste.ini is updated to use them.

KeystonAuthContext middleware is updated so that it uses
request-id generated by RequestIdMiddleware.

Add middleware to openstack.conf and import all modules
under middleware directory from oslo.

DocImpact UpgradeImpact
This patch adds new WSGI middlewares "request_id" and "catch_errors".
They needs to be added to api-paste.ini when upgrading.

Change-Id: Icf01b7de697ef50bef53212da2cf520d1ff78b88
Closes-Bug: #1239923
Merge "Return request-id in API response"