pip_verbose: add support for lang query parameter

[Joxit]

Background

I was looking for inspiration to replace my PR #75 and found this API which seems to have a good base to be used as the default API (/query/pip/verbose).

I know that we have some issue with multi-lang and autocomplete (see pelias/api#1296), having parent members in a defined language may help those who need autocomplete to work in a different lang than English.

What's new ?

I added a query parameter lang that accept iso 6391 (2 chars) and iso 6393 (3 chars) codes. Instead of using und lang it will return the requested language.
The name uses will not be in aliases when selected.

Small example from a request in France using Dutch /query/pip/verbose?lon=2.344576377568282&lat=48.876457644366816&lang=nl

{
"country": [
    {
      "id": "85633147",
      "source": "wof",
      "name": "Frankrijk",
      "abbr": "FRA",
      "centroid": {
        "lat": 46.7153185,
        "lon": 2.1843152
      },
      "bounding_box": "-61.797841,-21.370782,55.854503,51.089382"
    }
  ],
  "localadmin": [
    {
      "id": "1159322569",
      "source": "wof",
      "name": "Parijs",
      "centroid": {
        "lat": 48.8590265,
        "lon": 2.3200487
      },
      "bounding_box": "2.224225,48.815607,2.469769,48.902008"
    }
  ]
}

closes #75