Make a bunch of API changes.

README.md

Index: README.md
diff --git a/README.md b/README.md
index 23be5ff2047324bf4312934f7b6612152f3996b5..7e390cd4cbad2161384a263243a4602a9d46cb58 100644
--- a/README.md
+++ b/README.md
@@ -64,13 +64,15 @@ Future<oauth2.Client> getClient() async {
   if (exists) {
     var credentials = new oauth2.Credentials.fromJson(
         await credentialsFile.readAsString());
-    return new oauth2.Client(identifier, secret, credentials);
+    return new oauth2.Client(credentials,
+        identifier: identifier, secret: secret);
   }
 
   // If we don't have OAuth2 credentials yet, we need to get the resource owner
   // to authorize us. We're assuming here that we're a command-line application.
   var grant = new oauth2.AuthorizationCodeGrant(
-      identifier, secret, authorizationEndpoint, tokenEndpoint);
+      identifier, authorizationEndpoint, tokenEndpoint,
+      secret: secret);
 
   // Redirect the resource owner to the authorization URL. This will be a URL on
   // the authorization server (authorizationEndpoint with some additional query