Wirecloud-keycloak

- Show alert message only if we are in WireCloud 1.4 and we are not in embedded mode.

Fix some problems when using `django-compressor`

Added support for single sign on using the `check_status_iframe`, complementing the backchannel logout feature.

Add some logging messages

- Fix auth token injection when using WireCloud's proxy
- Use `kc_locale` param to use the same locale on Keycloak than in WireCloud when logging

- Move social auth backend to be based on the base OpenIDConnect backend.
- Now public keys are retrieved from the OIDC endpoints instead of having to use environment variables.
- Initial support for the backchannel logout feature from Keycloak.
- Move all Django settings to follow social auth naming pattern.