This change:
1. Adds credmanager service which handles credentials for AWS drivers.
2. Adds support for managing multiple AWS accounts through use of credmanager. Each account is mapped to a single project in keystone.
3. Adds support for multiple AZs by running one nova-compute and cinder-volume process per AZ.
4. Improves support for AWS networking in neutron.
5. Also, made few stability fixes in GCP and Azure drivers.
Change-Id: I0f87005a924423397db659ab754caaa6cde90274
3fc8b3f97d