Description of problem:
The quota can be abused by creating image steam tags

Version-Release number of selected component (if applicable):
openshift v1.1.3-536-gda71953
kubernetes v1.2.0-alpha.7-703-gbc4550d
etcd 2.2.5

How reproducible:
always

Steps to Reproduce:
1. To apply a quota to a project:
more resource-quota.json 
{
  "apiVersion": "v1",
  "kind": "ResourceQuota",
  "metadata": {
    "name": "quota"
  },
  "spec": {
    "hard": {
      "memory": "1Gi",
      "cpu": "20",
      "openshift.io/imagesize": "0.2Gi",
      "openshift.io/imagestreamsize": "0.2Gi",
      "openshift.io/projectimagessize": "0.2Gi",
      "pods": "10",
      "services": "5",
      "replicationcontrollers":"5",
      "resourcequotas":"1"
    }
  }
}

`oc create -f resource-quota.json -n zhouy`

2. Tag a public registry image to the project, the image size is 160M;
  `docker tag docker.io/zhouying7780/singlelayer hellotest:latest`
3. Push the image to integrated docker-registry.
4. Tag the ImageStream with another tag:
   `oc tag hellotest:latest mybase:v2`
5. Push the new ImageSteam again.
6. Check the quota info.

Actual results:
5. Push successfully;
6. The quota info show that the Used of openshift.io/projectimagessize is bigger than the Hard of openshift.io/projectimagessize.
[root@ip-172-18-6-56 amd64]# oc describe quota
Name:                quota
Namespace:            zhouy
Resource            Used        Hard
--------            ----        ----
cpu                0        20
memory                0        1Gi
openshift.io/imagesize        0        214748364800m
openshift.io/imagestreamsize    0        214748364800m
openshift.io/projectimagessize    320204510    214748364800m
pods                0        10
replicationcontrollers        0        5
resourcequotas            1        1
services            0        5

Expected results:
The Used of openshift.io/projectimagessize should not exceed the Hard of openshift.io/projectimagessize.

Additional info: