Add drf-yasg

* Install drf-yasg

* Add drf-yasg settings and urls

* Pin drf to make drf-yasg work

* Adjust config-models version to be compatible

* Remove django-rest-swagger (the old way)

openedx/core/openapi.py

@@ -0,0 +1,22 @@
+"""
+Open API support.
+"""
+
+from rest_framework import permissions
+from drf_yasg.views import get_schema_view
+from drf_yasg import openapi
+
+openapi_info = openapi.Info(
+    title="Open edX API",
+    default_version="v1",
+    description="APIs for access to Open edX information",
+    #terms_of_service="https://www.google.com/policies/terms/",         # TODO: Do we have these?
+    contact=openapi.Contact(email="oscm@edx.org"),
+    #license=openapi.License(name="BSD License"),                       # TODO: What does this mean?
+)
+
+schema_view = get_schema_view(
+    openapi_info,
+    public=True,
+    permission_classes=(permissions.AllowAny,),
+)