Upgrade to PaymentMethods and API version 2019-03-14 (#62)

* Upgrade frontend and Node.js server to payment methods and API 2019-03-14.

* Upgrade Stripe Node library to latest.

* Upgrade Ruby server.

* Upgrade Python server.

* Update gcloud ignore file.

* Upgrade ngrok and morgan.

* Upgrade Java server.

* Upgrade PHP server.

* Shipping address on PRAPI.

.gcloudignore

@@ -13,13 +13,13 @@
 .git
 .gitignore
 
-# Node.js dependencies:
+# Node.js dependencies
 node_modules/
 
-# Python server
+# Alternative server implementations
+server/java/
+server/php/
 server/python/
-
-# Ruby server
 server/ruby/
 
 # serverless functions