Update to requests>=1.0.0 for keystoneclient.

The requests module dropped all configuration with the 1.0.0 release.
There's no danger_mode and no 'verbose'' mode. The former shouldn't
be necessary anymore and the latter can be done by setting a different
log handler for the request.logging root logger.

Related to https://review.openstack.org/#/c/20127/

Change-Id: Ide43a41b5481daede96e142d1a4f6519e33c21bf
Merge "Update to requests>=1.0.0 for keystoneclient."