Users can define `label_colors` in a dashboard's JSON metadata that
enforces a label to color mapping.
This also makes the function that maps labels to colors case insensitive.
* DECKGL integration
Adding a new set of geospatial visualizations building on top of the
awesome deck.gl library. https://github.com/uber/deck.gl
While the end goal it to expose all types of layers and let users bind
their data to control most props exposed by the deck.gl API, this
PR focusses on a first set of visualizations and props:
* ScatterLayer
* HexagonLayer
* GridLayer
* ScreenGridLayer
* Addressing comments
* lint
* Linting
* Addressing chri's comments
* Allow for multiple color schemes
1. create ColorSchemeControl component
2. using the same new control component for linear colors
* add color spectum for linear color scheme
* remove dup css
* fix controls setting for linear color scheme
* minor fix by code review comment
