Deploying a Polymer app to Google App Engine

The steps that are required to deploy a Polymer app to Google App Engine are documented and there is no need to repeat them here.  However, some changes are required to make everything work end to end.

First, polymer build command creates an unbundled output and places it to build/default folder. GAE seems to serve resources via HTTP/2 with server push just fine, so there is no need to create create a bundled output.

Second, since all output files by default are in build/default folder, you need to change static_files in app.yaml file  from build/bundled/... to build/default/....  Another option is to simply rename build/default folder to build/bundled folder.

Third, appcfg.py -A {project name} update app.yaml will more likely fail.  I had to add --oauth2 option for deployment to succeed:  appcfg.py --oauth2 -A {project name} update app.yaml