Add viewport method to results that provide one

Warn that the Yahoo BOSS Placefinder API is being discontinued.

https://developer.yahoo.com/boss/placefinder/

the Yahoo lookup will be fully removed via:
https://github.com/alexreisner/geocoder/pull/985

Add adapter for geoportail.lu (Luxembourg)

Require lookups only as they are used.

Fix Geocoder::Calculations.endpoint comment

I just spent a few hours trying to get this function to work, then realized I had my parameters in the wrong order. I was following the order listed in the comment, rather than the actual method definition! *facepalm* Anyhow, this fixes the comment, for the next person to read it.

Removed 'LIMIT 1' in maxmind local lookup that prevented from using database index.

For #928

Google geocoder results - expose partial_match and place_id fields

Add place_name and place_type to esri result

This reverts commit 97b6bb94.

Retrieve city when esri query returns a city POI

Explain what exactly `:order => false` does.

update readme to state how to use ':order => false'