[WIP] Service 'query' on layers

This is the service part for the layer attributes search.

It is based on the _ArcGIS REST API_,

http://resources.arcgis.com/en/help/arcgis-rest-api/index.html#/Query_Feature_Service_Layer/02r3000000r1000000/


1/ Layer attributes informations

The type of attribute and its translation (if present)  is also returned:

http://mf-chsdi3.int.bgdi.ch/mom_query_attributes/rest/services/api/MapServer/ch.bafu.bundesinventare-bln

```
{
    fields: [{
        alias: "bln_name",
        type: "TEXT",
        name: "bln_name"
    }, {
        alias: "bln_obj",
        type: "INTEGER",
        name: "bln_obj"
    }, {
        alias: "bln_fl",
        type: "NUMERIC",
        name: "bln_fl"
    }],
    id: "ch.bafu.bundesinventare-bln",
    name: "IFP"
}
```

2/ Query attributes

For now only the **where** and **geometry** are implemented.

**where**
[objects with surface > 100](http://mf-chsdi3.int.bgdi.ch/mom_query_attributes/rest/services/api/MapServer/ch.bafu.bundesinventare-bln/query?where=bln_fl < 100 )

[objects with name like 'Domat'](http://mf-chsdi3.int.bgdi.ch/mom_query_attributes/rest/services/api/MapServer/ch.bafu.bundesinventare-bln/query?where=bln_name ilike '%Domat%')

[object combining both filters](http://mf-chsdi3.int.bgdi.ch/mom_query_attributes/rest/services/api/MapServer/ch.bafu.bundesinventare-bln/query?where=bln_fl < 50 and bln_name ilike '%Domat%')

Spatial filter (**geometry**, a geojson object)

[objects within a geometry](http://mf-chsdi3.int.bgdi.ch/mom_query_attributes/rest/services/api/MapServer/ch.bakom.mobil-antennenstandorte-gsm/query?where=powercode%20like%27%%27&geometry={%22type%22:%20%22MultiPolygon%22,%20%22coordinates%22:%20[[[[600000,%20200000],%20[620000,%20200000],[620000,%20220000],[600000,%20220000],[600000,%20200000]%20]]]})