authenticate: use gRPC for service endpoints (#39)

* authenticate: set cookie secure as default.
* authenticate: remove single flight provider.
* authenticate/providers: Rename “ProviderData” to “IdentityProvider”
* authenticate/providers: Fixed an issue where scopes were not being overwritten
* proxy/authenticate : http client code removed.
* proxy: standardized session variable names between services.
* docs: change basic docker-config to be an “all-in-one” example with no nginx load.
* docs:  nginx balanced docker compose example with intra-ingress settings.
* license:  attribution for adaptation of goji’s middleware pattern.

internal/middleware/middleware.go

@@ -119,7 +119,7 @@ func ValidateHost(mux map[string]http.Handler) func(next http.Handler) http.Hand
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			if _, ok := mux[r.Host]; !ok {
-				httputil.ErrorResponse(w, r, "Unknown host to route", http.StatusNotFound)
+				httputil.ErrorResponse(w, r, "Unknown route", http.StatusNotFound)
 				return
 			}
 			next.ServeHTTP(w, r)