- customize bootcd and bootmanager

- customize bootcd and bootmanager
- use bash v2 ${!variable} syntax instead of kludgy evals
- config_ssl: regenerate self-signed certificate if hostname changes, or
  the certificate expires. Check if have already have a self-signed
  certificate for the same hostname before deciding to generate a new
  one, since name-based virtual hosting doesn't work with SSL.
- allow the API, web, and boot servers to run on different ports