Updates for the Developer Portal (GoogleCloudPlatform#589)

Updates so the sample API can be used easily in the Developer Portal. 
-- In schemes, it has to be "http" so that you can test the echo API in the Developer Portal. 
-- In the echoMessage definition, adding type: "object" provides a better user experience in the Developer Portal.

Author: navinger

endpoints/getting-started/openapi.yaml

@@ -11,7 +11,9 @@ consumes:
 produces:
 - "application/json"
 schemes:
-- "https"
+# Uncomment the next line if you configure SSL for this API.
+#- "https"
+- "http"
 paths:
   "/echo":
     post:
@@ -62,6 +64,7 @@ paths:
 
 definitions:
   echoMessage:
+    type: "object"
     properties:
       message:
         type: "string"