Remove natural_forest and natural_wood from pois layer

[nvkelso]

These should only be label placements in the landuse layer but are now appearing in the pois layer.

  # natural forests - note already clamped to z12
  - filter: {natural: forest}
    min_zoom: { min: [ { max: [ 12, { lit: zoom + 2 }, { lit: *tier2_min_zoom } ] }, 14 ] }
    output: { kind: natural_forest, tier: 2 }

  # natural woods - note already clampted to 12
  - filter: {natural: wood}
    min_zoom: { min: [ { max: [ 12, { lit: zoom + 2 }, { lit: *tier2_min_zoom } ] }, 14 ] }
    output: { kind: natural_wood, tier: 2 }

Example:

• http://tile.dev.mapzen.com/mapzen/vector/v1/all/14/8184/5448.topojson

{
type: "Point",
properties: {
kind: "natural_wood",
area: 2426,
source: "openstreetmap.org",
min_zoom: 14,
tier: 2,
id: -1756198,
osm_relation: true
},
coordinates: [
388,
933
]
},

Curious that we're even showing those without any names!

[nvkelso]

Possibly also village_green?