start implementing multiple modes for operation

- synapse: Only trigger register calls and do not store anything for longterm
- local: Provide an identity store and register to the own backend

config.sample.php

@@ -11,7 +11,13 @@ $config = [
     "webroot" => "https://myregisterdomain.net/",
     // optional: Do you have a place where howTo's are located? If not leave this value out
     "howToURL" => "https://my-url-for-storing-howTos.net",
+    // set the mode of operation. Basically this defines where the data is stored:
+    // - synapse (using the register endpoint - so no further auth config necessary
+    // - local (recommended; using a table in the database to store credentials;
+    //   synapse has to be configured to use that)
+    "operationMode" => "local",
     // When you want to collect the password on registration set this to true
+    // only evaluated when operationMode = local
     "getPasswordOnRegistration" => false,
     // to define where the data should be stored:
     "databaseURI" => "sqlite:" . dirname(__FILE__) . "/db_file.sqlite",