Description of problem:
After provision apb mediawiki, the PVC met invalid AccessModes error

Version-Release number of selected component (if applicable):
asb: 0.9.4
openshift v3.6.135
kubernetes v1.6.1+5115d708d7
etcd 3.2.1

How reproducible:
Always

Steps to Reproduce:
1. Run the script to provision mediawili service.
# cat provision.sh 
#!/bin/bash -e

instanceUUID="bdeb07ca-2da8-4742-9312-561c6ec86ae0"
planUUID="4c10ff42-be89-420a-9bab-27a9bef9aed8"
serviceUUID="55c53a5d-65a6-4c27-88fc-e027410b1337"

req="{
  \"plan_id\": \"$planUUID\",
  \"service_id\": \"$serviceUUID\",
  \"context\": {
    \"platform\": \"kubernetes\",
    \"namespace\": \"mediawiki-project\"
  },
  \"parameters\": {
    \"mediawiki_db_schema\": \"mediawiki\",
    \"mediawiki_site_name\": \"mediawiki\",
    \"mediawiki_site_lang\": \"en\",
    \"mediawiki_admin_user\": \"admin\",
    \"mediawiki_admin_pass\":\"redhat\"
  }
}"

curl \
  -X PUT \
  -H 'X-Broker-API-Version: 2.9' \
  -H 'Content-Type: application/json' \
  -d "$req" \
  -v \
  "http://172.30.174.228:1338/v2/service_instances/$instanceUUID?accepts_incomplete=true"

2. Check pvc status
# oc get storageclass
NAME            TYPE
gp2 (default)   kubernetes.io/aws-ebs
# oc get storageclass gp2 -o json
{
    "apiVersion": "storage.k8s.io/v1",
    "kind": "StorageClass",
    "metadata": {
        "annotations": {
            "storageclass.beta.kubernetes.io/is-default-class": "true"
        },
        "creationTimestamp": "2017-07-06T04:06:59Z",
        "name": "gp2",
        "resourceVersion": "1726",
        "selfLink": "/apis/storage.k8s.io/v1/storageclasses/gp2",
        "uid": "8e9dabee-6200-11e7-8615-0e7aca344840"
    },
    "parameters": {
        "type": "gp2"
    },
    "provisioner": "kubernetes.io/aws-ebs"
}
# oc get pvc -n mediawiki-project
NAME               STATUS    VOLUME    CAPACITY   ACCESSMODES   STORAGECLASS   AGE
mediawiki123-pvc   Pending                                      gp2            1m
# oc describe pvc/mediawiki123-pvc -n mediawiki-project
Name:        mediawiki123-pvc
Namespace:    mediawiki-project
StorageClass:    gp2
Status:        Pending
Volume:        
Labels:        <none>
Annotations:    volume.beta.kubernetes.io/storage-provisioner=kubernetes.io/aws-ebs
Capacity:    
Access Modes:    
Events:
  FirstSeen    LastSeen    Count    From                SubObjectPath    Type        Reason            Message
  ---------    --------    -----    ----                -------------    --------    ------            -------
  1m        13s        8    persistentvolume-controller            Warning        ProvisioningFailed    Failed to provision volume with StorageClass "gp2": invalid AccessModes [ReadWriteMany]: only AccessModes [ReadWriteOnce] are supported

3.

Actual results:


Expected results:
2. PVC is Bound success

Additional info:
https://github.com/fusor/apb-examples/blob/master/mediawiki123-apb/roles/provision-mediawiki123-apb/tasks/main.yml#L23-L24