This patch splits openshift-client task from the openshift-client directory

Changes include:
  - moves the openshift-client task to the task directory
  - copies and modifies readme file for openshift-client task from openshift-client directory
  - copies OWNERS file from openshift-client directory
  - changes the yaml filename to match the resource name

Issue: #386

Signed-off-by: Shiv Verma <shverma@redhat.com>

task/openshift-client/0.1/OWNERS

@@ -0,0 +1,7 @@
+approvers:
+- vdemeester
+- piyush-garg
+reviewers:
+- vdemeester
+- piyush-garg
+- chmouel

task/openshift-client/0.1/README.md

@@ -0,0 +1,53 @@
+## OpenShift Client Task
+
+[OpenShift](http://www.openshift.com) is a Kubernetes distribution from Red Hat which provides `oc`, the [OpenShift CLI](https://docs.openshift.com/container-platform/4.1/cli_reference/getting-started-cli.html) that complements `kubectl` for simplifying deployment and configuration applications on OpenShift.
+
+Openshift-client runs commands against the cluster where the task run is being executed
+
+
+## Install the Task
+```
+kubectl apply -f https://raw.githubusercontent.com/tektoncd/catalog/master/task/openshift-client/0.1/openshift-client.yaml
+```
+
+## Parameters
+
+* **ARGS:** args to execute which are appended to `oc` e.g. `start-build myapp` (_default_: `help`)
+
+* **SCRIPT:** script of oc commands to execute  e.g. `oc get pod $1 -0 yaml` This will take the first value of ARGS as pod name (_default_: `oc $@`)
+
+
+## Resources
+
+### Inputs
+
+* **cluster**: a `cluster`-type `PipelineResource` specifying the target OpenShift cluster to execute the commands against it
+
+## ServiceAccount
+
+If you don't specify a service account to be used for running the `TaskRun` or `PipelineRun`, the `default` [service account](https://kubernetes.io/docs/tasks/configure-pod-container/configure-service-account/#use-the-default-service-account-to-access-the-api-server). OpenShift by default does not allow the default service account to modify objects in the namespace. Therefore you should either explicitly grant permission to the default service account (by creating rolebindings) or [create a new service account with sufficient privileges](https://kubernetes.io/docs/reference/access-authn-authz/rbac/#service-account-permissions) and specify it on the [`TaskRun`](https://github.com/tektoncd/pipeline/blob/master/docs/taskruns.md#service-account) or [`PipelineRun`](https://github.com/tektoncd/pipeline/blob/master/docs/pipelineruns.md#service-account).
+
+You can do the former via `oc` and running the following command, replacing `<namespace>` with your target namespace:
+```
+oc policy add-role-to-user edit -z default -n <namespace>
+```
+
+## Usage
+
+This `TaskRun` runs an `oc rollout` command to deploy the latest image version for `myapp` on OpenShift.
+
+```
+apiVersion: tekton.dev/v1beta1
+kind: TaskRun
+metadata:
+  name: deploy-myapp
+spec:
+  taskRef:
+    name: openshift-client
+  params:
+  - name: ARGS
+    value:
+      - "rollout"
+      - "latest"
+      - "myapp"
+```