Implement working "hello world" Task + TaskRun

[bobcatfish]

Expected Behavior

A user should be able to create a "hello world" Task that just echoes "hello world" and run it as many times as they like in their k8s cluster by creating TaskRuns.

Requirements:

• Test coverage (unit tests + if possible integration tests, may be blocked by Setup PR testing for build-pipeline integration tests #16 )
• Docs that explain how to run this Task, with examples
• Docs that explain how to debug this (i.e. where to look if it goes wrong)

Actual Behavior

It is possible to get something like this working with Build only, but currently our TaskRun controller does nothing.

Steps to Reproduce the Problem

1. Deploy the Pipeline CRD + related CRDs to your cluster (note: should be docs on how to do this post kubebuilder)
2. Create a task like this:

apiVersion: pipeline.knative.dev/v1beta1
kind: Task
metadata:
  name: helloworld-task
  namespace: default
spec:
    buildSpec:
        steps:
            - name: helloworld
              image: busybox
              args: ['echo', 'hello world'']

3. Create a task run like this:

apiVersion: pipeline.knative.dev/v1beta1
kind: TaskRun
metadata:
  name: helloworld-task-run-0
spec:
    taskRef:
        name: helloworld-task
    trigger:
        triggerRef:
            type: manual

4. Look at the logs from the running container (Note the best docs we have on this at the moment are some of the steps in the Build quick start) - these should contain "hello world"
5. Observe that the status of the TaskRun has been updated appropriately, e.g. see this example which contains:

• Outcomes of individual steps
• Started, Completed, and Successful conditions

[nader-ziada]

in the example above, in step (3) should the name of TaskRef be helloworldTask as indicated by the name defined for the task in step (2)
or is that name coming from somewhere else?

[bobcatfish]

in the example above, in step (3) should the name of TaskRef be helloworldTask as indicated by the name defined for the task in step (2)
or is that name coming from somewhere else?

Oh whoops, so in step (3) I think the name should be helloworld-task since that's what the Task is called. Thanks for catching that @pivotal-nader-ziada ! I've updated it, let me know if it still doesn't seem right.

[aaron-prindle]

fixed with #86