Finally ready for testing! 🎉 I've rewritten /sup-tree plugin to new graph library. Previously we were using vivagraphjs but it wasn't perfect for our needs. This PR changes it to sigmajs. It has better labels system, better layout algorithm (it still requires adjusting settings for our needs but it's easier to control it's behaviour than previously), easier renderer extensions. Potential issue could be distance between nodes when we have large graphs or when application has very small supervision tree.

Major changes are:

• Faster first render with big trees. Previously it took a lot to show graph, right now we show how layout if forming instead of waiting for correct positions before first render.
• Labels! 🎉 🎉 🎉 It's a lot easier to identify application when root supervisor has correct label!
• Create wrapper for plugin view which can be reused between other plugins. It adds unified loader and resizable right side panel. In future it would be possible to create better API for side panels on every side (top, bottom, left, right) as well as option to toggle anyone of them on and off.
• Circle nodes (instead of square)! Other shapes possible, up to discussion ☺️

Right now it's still work in progress but core features are done so I'm counting on your feedback!

• center camera on application when selecting
• fix selecting nodes when layout is still forming
• dragging nodes (I've started working on it and may be complicated, I don't know how it will play with layout algorithm)
• update side panel layout and style (It's very raw right now, needs more polishing)
• toggle labels (when we have a lot of workers in one place it gets messy, needs ability to disable/enable labels rendering)