Restructure Alliance Auth package (#867)

* Refactor allianceauth into its own package

* Add setup

* Add missing default_app_config declarations

* Fix timerboard namespacing

* Remove obsolete future imports

* Remove py2 mock support

* Remove six

* Add experimental 3.7 support and multiple Dj versions

* Remove python_2_unicode_compatible

* Add navhelper as local package

* Update requirements

allianceauth/authentication/checks.py

@@ -0,0 +1,12 @@
+from django.core.checks import Error
+from django.conf import settings
+
+
+def check_login_scopes_setting(*args, **kwargs):
+    errors = []
+    try:
+        assert settings.LOGIN_TOKEN_SCOPES
+    except (AssertionError, AttributeError):
+        errors.append(Error('LOGIN_TOKEN_SCOPES setting cannot be blank.',
+                            hint='SSO tokens used for logging in must require scopes to be refreshable.'))
+    return errors