Initial OpenStack client plugin for Search

Summary
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We need an initial OpenStack client plugin for searchlight.

Motivation
========
OpenStack client is the single CLI go forward for OpenStack. You add to it by making a plugin for the OpenStack Client. Plugins are described below:

http://docs.openstack.org/developer/python-openstackclient/plugins.html

Description
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We need an initial OpenStack client plugin for searchlight. It should support basic search commands.

 - Get resource types
 - Open Query Search (just take query input)

Additional, more refined commands with per plugin named queries could come in follow on BP's

Proposed change
===============
There will be two parts of work items:

- searchlight client: Client for the searchlight v1 API
   #. Querying available plugins: list(**kwargs)
   #. Running a search: search(query=None, index=None, type=None, _source=None, offset=None, limit=None, highlight=None, sort_order=None, all_projects=None, **kwargs)
   #. Faceting list: list(all_projects=None, type=None, **kwargs)

- openstack client plugin: will call the searchlight client to implement the following commands:
   #. openstack searchlight plugin list
   #. openstack searchlight search
   #. openstack searchlight facet list

The code base should be like:
├── searchlight
│   ├── client
│   │   ├── common
│   │   └── v1
│   ├── osc
│   │   └── v1

Testing
======
Brief instruction for reviewers to exercise the changes, including expected results where non-obvious.

Outside Dependencies
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Is this functionality already supported in other services? List the appropriate API calls and if they are extensions or base API functionality.

This should describe any cross project dependencies. This should include:
  * changes to OpenStack services
  * changes to OpenStack services clients (python-*client)
  * changes in external projects
Links to particular patches should be included in the whiteboard area.

Requirements Update Required
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