Automatic merge from submit-queue

Add local storage (scratch space) allocatable support

This PR adds the support for allocatable local storage (scratch space).
This feature is only for root file system which is shared by kubernetes
componenets, users' containers and/or images. User could use
--kube-reserved flag to reserve the storage for kube system components.
If the allocatable storage for user's pods is used up, some pods will be
evicted to free the storage resource.

This feature is part of local storage capacity isolation and described in the proposal https://github.com/kubernetes/community/pull/306

**Release note**:

```release-note
This feature exposes local storage capacity for the primary partitions, and supports & enforces storage reservation in Node Allocatable 
```