Make #near_scope_options public for Rails 5.2

Rails 5.2 changed the receiver within a scope from `klass` to
`relation`. With that, we no longer have private access to
Geocoder::Store::ActiveRecord#near_scope_options, and so must make it
public.

see: https://github.com/rails/rails/pull/29301

This reverts commit 385aafa0.

Should have been part of 7cb0acc9

Should have been part of 7cb0acc9

HTTP support will be discontinued according to this:
https://lists.openstreetmap.org/pipermail/geocoding/2018-January/001918.html

Fixes #1267

for Google Premier. No longer required, according to this page:
https://developers.google.com/maps/premium/overview

Fixes #1268

Update geocod.io to use most recent API version

Updated geocod.io description to reflect that it also supports Canada

see: https://github.com/alexreisner/geocoder/pull/1254#issuecomment-359118927

suggested by @alexreisner

Raise bing errors for statuses 403, 500, 503

Bing returns the status codes within the json response. When a request is
forbidden, it will return a 403. If there is an internal server error,
it will return a 500. And if the service is unavailable for some other
reason, it will return a 503. That information was obtained from bing's
[Status Codes and Error
Handling](https://msdn.microsoft.com/en-us/library/ff701703.aspx)
documentation.

We handle those three status codes here to raise
`Geocoder::RequestDenied` (for 403) and `Geocoder::ServiceUnavailable`
(for 500 and 503). This allows for the users of the Geocoder to handle
those errors in their applications.

Fix Travis CI build errors. Closes #1224

Remove silly check for HTML tags
Add test case for invalid json

Handle IPv6 addresses when removing port numbers in request.location. Closes #1210

Fixes #1243.

* Handle Geocoder::OverQueryLimitError gracefully.

Geocoder::OverQueryLimitError errors were not being generated correctly, and the response was coming back empty but with no indication.

This changes the behavior slightly so that unknown errors are also returned.

* Add error handling tests

* Remove unnecessary config in tests

* Update Mapzen and Pelias links

* add monthly free limits

* Update docs to include additional Mapbox options

Support for additional query params was added with commit
844da1c11c2e74777ee8aab40cf82cee0f68dfa8 but this was not reflected in
the documentation.

* Remove duplicate info; use consistent wording

Removed an unneeded example from the Mapbox docs & use a single level of
indentation. Also, change "options" to "params" in both the Google and
Mapbox examples.

Services readme update

realized most other providers do not include links to pricing pages so I wanted to remain consistent with that

updated docs for several street service providers to reflect current pricing, and eliminated geocoder.us as it appears to no longer exist