In Scope

• Pipeline graph, activity list, branch list and result screen needs to communicate somehow that the pipeline is blocked and waiting for input
• Developer will need some way of providing the input (dialog with a form?) and a way of triggering the input form.

Notes
A pipeline can block for user input at any point.

The input can take the form of Yes/No to continue or fail the current run.
It can also ask for some piece of input from a user (which may be a choice, a password or other things).

Currently the Jenkins 2.0 stage view shows only the Yes/No case, but ideally blue ocean will be able to show the other forms of approval.

This form will be used both when the user clicks on the "waiting for input" card, or from the railroad.

(this is both a design task, but an API will likely be needed for this).