Fixes #1299.

and remove separate #latitutde and #longitude methods (which are defined
in base Result class).

* Update initializer template to use ipinfo_io

* Implement ipstack lookup

* Add Ipstack readme documentation

* Add post-install message

* Remove DSL from ipstack lookup

* Remove unnecessary logging

* Update post-install message

Fixes #1286.

Freegeoip/IPstack no longer provides keyless service.

Update Geocodio to v1.3

Fixes #1273.

some google geocoding requests have bounds within the result.  add a
helper to extract these.

* Add tests to cover results with no bounds

In this case, calling .bounds should return nil.  Oddly, calling
viewport on a result with no viewport causes the current code to `fail`.
I have preserved this behavior even though I think it to be a little
odd.

but default to HTTPS (custom hosts may not support HTTPS).
This partially reverts 7cb0acc9.

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

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

suggested by @alexreisner

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.

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

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

* Add support for DB-IP.com geocoding service

* Added support for https with paid accounts

* Use `use_https` to distinguish between paid/unpaid API usage

* Clean rubocop warnings

* Update LocationIQ geocoding provider with limits and handle errors

* Correct syntax errors

* Update over limit fixture

* Set HTTPS as the assertion for the URL

* Add missing fixtures for unit tests

* Correct the mistakes in doc

* Let users decide SSL usage

* Revert incorrectly asserted URL without https

* Remove use_ssl from lookup subclass

* Update the assertion of the URL to HTTP and not HTTPS

This is a better way to force HTTPS.

* Allows radius to be a symbol representing a column in DB

* Proposed changes by @alexreisner:

- Keeping branching condition consistent
- Not overwrite the method argument: ‘radius’
- Not assigning two variables in a single line, and
- Add code comments where needed

By “proposed” I meant, I copy/paste them from his comment. But we are
in agreement.

* Fixes broken test in PR