pipeline does not pass rv-object to final callback

[nickziv]

As a result of the work on issue-32, the underlying implementations for pipeline() and waterfall() were refactored. During this refactor, a bug was introduced in which the pipeline() function does not pass the status-object to its final callback. This also affects anything else that's implemented in terms of pipeline(), such as forEachPipeline(). Solution involves adding a new res_type to the opts object we pass to waterfall_impl().

Also, please avoid using version 2.0.0 of vasync, if possible.

[nickziv]

This bug snuck in, because we didn't have (and I didn't write) pipeline tests. Instead I relied exclusively on waterfall and tryEach tests. This was insufficient, and have added a pipeline test to the tests/ directory which verifies that pipeline is running correctly. It gets executed via the same npm test command as the other tests.

Furthermore, a branch of sdc-docker now doesn't crash with this version of vasync. Our other services are unaffected since they are pinned to older versions.