Related to #147

Expected Behavior

As a former Build user, I should be able to create a single resource that executes requested steps and can be watched for updates.

Actual Behavior

If I want to run some steps, I first have to define a Task that specifies those steps, then invoke it with a TaskRun that references that Task.

Additional Info

One possible solution would be to have the TaskRun type take either a taskRef or a taskSpec (but not both, or neither). When a TaskRun is requested with a taskSpec, it would perform the same steps as if a Task had been created with the given spec, then invoked by the TaskRun, without creating a Task as a side effect. Tasks defined in this way can't specify parameters, but can specify inputs. Resources might also need to be able to be defined without referencing a pre-existing CRD resource.