Better configuration DSL

[gshutler]

Get rid of the << style, something along the lines of this suggested by @sbellware

Hatchet.configure do |config|
  config.level :warn
  config.level :debug, 'Application::BankTransfer'

  config.appender(Hatchet::LoggerAppender.new) do |appender|
    appender.logger = Logger.new('log/application.log')
  end

  config.appender(CustomEmailAppender.new) do |appender|
    appender.level :fatal
    appender.formatter = CustomEmailFormatter.new
    appender.recipient = '[email protected]'
  end
end

May be able to avoid the .new by checking if the parameter is a class or an object to neaten up a little more in the common case.