BiG-CZ: Update Search Endpoint to Accept GeoJSON and WKAoI

[rajadain]

As of #2246, we are sending the full geometry of the area of interest for searching, in a payload akin to this:

{
  "catalog": "cinergi",
  "query": "water",
  "geom": {
    "type": "MultiPolygon",
    "coordinates": [
      [
        []
      ]
    ]
  },
  "from_date": null,
  "to_date": null
}

To better match the API design used for the new Geoprocessing API (#2201), make it so this endpoint accepts GeoJSON in the POST body, and all other parameters (catalog, query, from_date, to_date) are in the query.

Also, add a wkaoi query parameter, that if present with an empty POST body, causes a lookup of a well-known AoI by that name. If no such entry is found, the endpoint should return a 404.

If neither a wkaoi nor a valid GeoJSON is found in the POST body, then return a 400.

[rajadain]

As of #2258, we have a good common framework for filters, but are still constructing the parameters in a level above (in startSearch). The filters would be easier to work with / compose if they could provide their own parameters, so we could do something like this:

var geom = this.get('geom'),
    query = this.get('query')
    getParams = function (x) { x.getParams(); },
    params = this.get('filters').map(getParams).join('&'),
    url = BASE_URL + '?query=' + query + '&' + params;

$.post(url, geom);