* Workaround for multi-backend.
There is currently an issue with creating the BackendManager which has a backend instance. This instance is not used by the uploader, so they will create new instances.
The BackendManager instance can then time out, but is used later.
This commit will allow the uploader to "borrow" the instance from the backend manager, so only a single instance is needed.
This is not a clean fix, but doing so requires a full rewrite of the backend manager and uploader, so the controller creates a single instance of the manager, which is then used for all operations.
This would allow the backend manager to keep track of instances across all requests.
* Improved reuse after shutdown
