Add changes in conditions of use yandex geocoding API to the README

See [this post](http://clubs.ya.ru/mapsapi/replies.xml?item_no=58741)
and also [documentation](https://tech.yandex.ru/maps/doc/geocoder/desc/concepts/input_params-docpage/) for the details

Sorry for unable to provide link to the english version.
Seems that changes are not reflected in the [english documentation](https://tech.yandex.com/maps/doc/geocoder/desc/concepts/input_params-docpage/) yet

Emphasize form of coordinates in README

Looking through the README, the only mention of the format of `coordinates` was under the MongoDB section which is all the way at the bottom of the file.

Ruby warnings

Minor typo fix in the README

Test against different versions of rails

Fixes GH #907.

Fix #906 - Use different memoization variables for request

safe_location and location should not rely on the same variable,
otherwise calling one before the other will yield unexpected results
and could even cause a security risk if location is called before
safe_location

See GH #832.

Not pretty, but it fixes out-of-the-box verbosity issues (see GH #881).

Updated geocodio description

Updated description with additional details

Conflicts:
	lib/geocoder/lookups/base.rb

Test was failing for irrelevant reasons.

This reverts the parts of commit 350567f5
that are outside of the README and should not have been included.

See: http://clubs.ya.ru/mapsapi/replies.xml?item_no=56858

Fix yandex geocoder redirect to https

logger configuration is incompatible with Rails.logger (not really)

Updated Bing offering