Support multiple (batch) copy in Horizon Object Storage Module

Summary
=======
Implementation of a batch copy feature for objects from a container to another in the Object Store module.

Motivation
========
Promote user usability and operation consistency between all modules in Horizon.

Description
=========
To maintain the usability of Horizon and the quality of the UX it should be possible for an user to copy more than one object from the Object Store policy at once from one container to another. This change would improve the storage management operation usability from within Horizon.
The user should be able to select more than one object and copy them all in a batched operation to a container of his choice. The user would then be able to name the copied objects one by one if he wants to or remove them from the copy list.

Iteration 1: Have the multiple object copy modal ready with the container and path options available. In this iteration the objects names would be the same or would have an automatic suffix like '.copy'. In this iteration there would be no copy name table.

Iteration 2: The features of iteration 1 plus the copy name table (see mock-up).

UX
===
A 'Copy Objects' button would be added besides 'Delete Objects' and a modal window would pop just like the current copy dialog for a single object. All the objects would be copied to the chosen container at once.

Testing
======
Try to copy multiple objects from a container to another. If all the objects are copied it works.

Mock-up
======
https://<email address hidden>/qiamdplH/

Requirements Update Required
========================
https://blueprints.launchpad.net/horizon/+spec/select-all-checkbox-object-containers

Doc Impact
=========
N/A