Authentication

- add AuthenticationController
- add AuthenticationService
- add AccountRegistryProperty
- add WebClient.accountRegistryAuthenticate to WebClientCalls.kt

http/authentication.http

@@ -0,0 +1,8 @@
+### account login
+POST {{hostname}}/login
+Content-Type: application/json
+
+{
+    "username": "username",
+    "password": "password"
+}