* 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

This reverts commit ffcb5552.

* Removing ruby versions that are not supported anymore from our travis matrix

* Remove 2.1.2 from travis matrix

* 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.

Add missing commas to hashes in test stubs.

Add coordinates for testing stubs to README

Update OpenCage Data README section

PickPoint already included such a link in their "Quota" line.

* 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

specify rails version for migrations

Add time_zone to Opencagedata result

for clarity (damn, the README has gotten awfully long).

Reverting back to freegeoip.net (from freegeoip.io) as
it appears to be the intended default host (see:
https://github.com/fiorix/freegeoip/issues/165).

Source: http://freegeoip.net/

* Add place_id search for Google search

* Add place_id example to wiki

* Update README.md

* fix

Link to configuration.rb in docs

Add source code and changelog links to gemspec