Add support for custom views

[patriksvensson]

Is your feature request related to a problem? Please describe.
Having two different teams share the same dashboard doesn't always make sense. It would be nice if we could define views that could be switched between in the UI.

Describe the solution you'd like
There could be a new section in the configuraion that defines the views.

{
    "$schema": "https://raw.githubusercontent.com/spectresystems/duck/master/schemas/v0.4.json",
    "collectors": [ ],
    "observers": [ ],
    "views": [
        {
            "name": "team_a",
            "title": "A-Team",
            "collectors": [
                "collector1", "collector2"
            ]
        },
        {
            "name": "team_b",
            "title": "B-Team",
            "collectors": [
                "collector1", "collector3"
            ]
        }
    ]
}