Runtime config attributes
  host
  port
  log
  debug
  synchronize
  application (rack builder block)
  mime_types
  resources (routing)
  handler (rack handler)

App-specific config attributes
  database
  reloadable
  session
  dependencies


# Runtime config provided by top-level configurations
multi_1/
    apps/
        blog/
        wiki/
    configurations/
        default.rb        # => Waves::Configurations::Default
        development.rb    # => Waves::Configurations::Development
        production.rb     # => Waves::Configurations::Production
    log/
    startup.rb


# First app loaded is used for runtime config.
# How/where do you specify the loading of apps at all?
multi_2/
    blog/
        configurations/
        startup.rb
        ...
    pages/
        configurations/
        startup.rb
        ...
    wiki/
        configurations/
        startup.rb
        ...