GitLab

New module implementing instance allocation to one of the available
backends. Allocation is performed based on memory and disk utilization.
Statistics for each backend are stored in DB and updated periodically.

Allocation can be customized by creating a new allocation strategy
and declaring it in BACKEND_ALLOCATOR_MODULE setting.

- Create command to create a backend (snf-manage backend_create)
- Create command to modify a backend (snf-manage backend_list)
- Create command to list backends (snf-manage backend_modify)
- Modify listservers command to display the backend that hosts the VM

Replace use of global RAPI client, with the cached client from the
VirtualMachine or Backend model.

Dispatch network actions to all backends.

- Create Backend model holding info about credentials, status and resources
- Add Backend as foreign key to VirtualMachine
- Create a cache of Backend clients (RAPI) for better performance

Rename backend_id field of VirtualMachine model to avoid conflict between the
backend that hosts the VM and the id that the VM will have on the backend.

Added log folder option / Now delete-stale deletes also stale networks / Fixed failed testcases output not "None"