Fixes that make this work:
* A change in Ruby (ce635262f5)
requires passing in the exact required length for OpenSSL keys and IVs.
* Ensure the secrets.yml is generated before any prepended modules are
loaded. This is done by renaming the `secret_token.rb` initializer to
`01_secret_token.rb`, which is a bit ugly but involves the least impact on
other files.
