Django-recaptcha

- Fixed widget attributes regression for Django \< 1.10.

- Support Django 1.11 in addition to 1.8, 1.9, and 1.10.

- Made reCAPTCHA test keys the default keys for easy use in
development. The captcha doesn't require any interaction, has a
warning label that it's for testing purposes only, and always
validates.

- Pass options as HTML data attributes instead of the
`RecaptchaOptions` JavaScript object in the default template. Custom
templates using `RecaptchaOptions` should migrate to using HTML data
attributes.

- Dropped support for old Django versions. Only the upstream supported
versions are now supported, currently 1.8, 1.9, and 1.10.
- Made recaptcha checking use SSL by default. This can be disabled by
setting `RECAPTCHA_USE_SSL = False` in your Django settings or
passing `use_ssl=False` to the constructor of `ReCaptchaField`.
- Made ReCaptchaField respect required=False

- Confirmed tests pass on Django 1.10. Older versions should still
work.
- Fixed a bug where the widget was always rendered in the first used
language due to `attrs` being a mutable default argument.