Implements one workitem of blueprint apis-for-nova-manage
This adds an extension that provides REST API for list/enable/
disable nova service. The interface ia accessed via
GET /v2/{tenant_id}/os-services
PUT /v2/{tenant_id}/os-services/enable
PUT /v2/{tenant_id}/os-services/disable
And the command:nova host-describe have implemented the functionality
of nova-manage service describe_resource. So we needn't add a REST
API for it.
DocImpact
Change-Id: I030a7e00b878d7931456e7e323db37b7c47fce48