Add Trello sample.

Author: Eric Koleda

samples/Trello.gs

@@ -0,0 +1,62 @@
+var CONSUMER_KEY = '...';
+var CONSUMER_SECRET = '...';
+
+/**
+ * Authorizes and makes a request to the Trello API.
+ */
+function run() {
+  var service = getService();
+  if (service.hasAccess()) {
+    var url = 'https://api.trello.com/1/members/me/boards';
+    var response = service.fetch(url);
+    var result = JSON.parse(response.getContentText());
+    Logger.log(JSON.stringify(result, null, 2));
+  } else {
+    var authorizationUrl = service.authorize();
+    Logger.log('Open the following URL and re-run the script: %s',
+        authorizationUrl);
+  }
+}
+
+/**
+ * Reset the authorization state, so that it can be re-tested.
+ */
+function reset() {
+  var service = getService();
+  service.reset();
+}
+
+/**
+ * Configures the service.
+ */
+function getService() {
+  return OAuth1.createService('Trello')
+      // Set the endpoint URLs.
+      .setRequestTokenUrl('https://trello.com/1/OAuthGetRequestToken')
+      .setAuthorizationUrl('https://trello.com/1/OAuthAuthorizeToken')
+      .setAccessTokenUrl('https://trello.com/1/OAuthGetAccessToken')
+
+      // Set the consumer key and secret.
+      .setConsumerKey(CONSUMER_KEY)
+      .setConsumerSecret(CONSUMER_SECRET)
+
+      // Set the name of the callback function in the script referenced
+      // above that should be invoked to complete the OAuth flow.
+      .setCallbackFunction('authCallback')
+
+      // Set the property store where authorized tokens should be persisted.
+      .setPropertyStore(PropertiesService.getUserProperties());
+}
+
+/**
+ * Handles the OAuth2 callback.
+ */
+function authCallback(request) {
+  var service = getService();
+  var authorized = service.handleCallback(request);
+  if (authorized) {
+    return HtmlService.createHtmlOutput('Success!');
+  } else {
+    return HtmlService.createHtmlOutput('Denied');
+  }
+}