Add new controller prop to LogViewer

[marionleborgne]

Allow passing a custom map controller (http://uber.github.io/react-map-gl/#/Documentation/advanced/custom-map-controller?section=overriding-the-default-map-controller) to LogViewer via a controller prop.

[Pessimistress]

You can achieve this by supplying your own view mode:

const CUSTOM_VIEW_MODE = {
    name: 'custom',
    initialViewState: {
      maxPitch: 60,
      pitch: 30
    },
    mapInteraction: {
      type: CustomController
    },
    tracked: {
      position: true,
      heading: true
    }
  }