Add REST API support for list/enable/disable nova services
Add REST API support for list/enable/disable nova services

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

n0ano/ganttclient