Entrypoint fix and Puma configuration update

• Create GNUPGHOME with -p to prevent failures if it already exists.

  If the GNUPGHOME existed but was empty, mkdir would fail without -p.

• Preload the frontend before forking off workers with preload_app!.

  Create GNUPGHOME with -p to prevent failures if it already exists. (We’ve been running our 2.7 instance with this specified on command line for some time already.)