Gerrit had 2 different ways to serve files locally: - start server.go web server - start gerrit binary with --polygerrit-dev flag Both implementations did the same handling for local files. This change removes --polygerrit-dev flag and related java implementation and instead a new option --dev-cdn is added. This option enables using cdn for static content. Change-Id: I40d4c6c048de018bc6d856c889d7ec59592282ed