Refactored original PipelineEditorPanel into PipelineStepEditorPanel.

Added a new PipelineEditorView base class that PipelineStepEditorPanel and PipelineBuilderPanel now extend.
Added the new PipelineStepEditorPanel as a view that can be toggled with the PipelineBuilderPanel view in the new PipelineEditorPanel.
Removed the Publish button and bottom toolbar from PipelineStepEditorPanel.
Refactored PipelineAppModel and PipelineStepEditorPanel::toJson.

Updated PipelineAppModel and the toJson methods in the PipelineStep panels and PipelineStepEditorPanel to return the more simplified JSON used by the PipelineCreator.
Updated the PipelineStepEditorPanel::configure and PipelineStep panels' setData methods to parse the new JSON format.
Refactored PipelineBuilderPanel::getPublishJson into the base PipelineEditorView class, since both PipelineBuilderPanel and PipelineStepEditorPanel are now using the same Pipeline JSON.