pipeline-stage-view plugin should be deprecated in favor of Blue Ocean.

As more and more people start using pipeline, the first view of it they see is pipeline-stage-view.  However, it is clear that this plugin cannot keep up with all the visualization requirements that people have for pipeline.  Blue Ocean is where all the effort for visualizing pipelines has been taking place.

I recommend that:

1.  On this plugin's documentation page, a clear deprecation warning be placed at the top, with a a link telling people to download Blue Ocean instead.

2.  pipeline-stage-view should be removed from the dependencies for the pipeline-plugin.

So for exisiting users of pipeline, they will still have it, but new users of pipeline won't see it.  Those users will have to explicitly install pipeline-stage-view themselves.