Django-recaptcha429

-----
. Added testing for Django 2.2 (no code changes needed).

-----
. Moved field based Google dev key check to an app ready registered security check.

-----

. Bugfix: Remove extra div in widget_v3 template

-----

. ReCAPTCHA v3 support added.
. Remove all mention of the V1 reCAPTCHA endpoint.
. Refactor client, fields and widgets code.
. Added widgets for each type of reCAPTCHA: ``V2 Checkbox``, ``V2 Invisible``, ``V3``
. Remove the need for the widget template to be selected based on certain settings values, each widget has its own template.
. Introduced a large number of new unit tests, update tests to make use of tox venvs.
. Regenerated po and mo files.

------------------

. Added testing for Django 2.1 (no code changes needed).
. Update the unit tests to no longer make use of reCAPTCHA v1.
. Added deprecation warnings for reCAPTCHA v1 support.
. Remove the need for RECAPTCHA_TESTING environment variable during unit testing.
. Added Invisible reCAPTCHA V2 support.

------------------

. Dropped support for Django < 1.11.
. Added testing for Django 2.0 (no code changes needed).