Sets a pipeline_id on a definition which passes through to the template

@mattgillooly Allows supplying a block to `#deploy_pipeline` and uses it in the deploy rake task.  Passes the pipeline ID through the definition to the template.
I would typically do this as:

```ruby
definition = yield(created_pipeline.id)
```

Mostly because it's more idiomatic Ruby, but it also means you can also leave out the `&block` in the method signature  and avoid the (in this case minor) overhead of turning the block into a Proc.