title: Symfony2 Monolog Settings for email and file logging
body: <p>I want to setup Symfony2 to send me an email for <code>critical</code> errors, but just log <code>error</code> level errors.  Will the following settings do that?</p>
  
  <pre><code>monolog:
      handlers:
          main:
              type:         fingers_crossed
              action_level: error
              handler:      grouped
          grouped:
              type: group
              members: [filelog, mail]
          # log all errors to file
          filelog:
              type:         fingers_crossed
              action_level: error
              handler:      nested_stream
          nested_stream:
              type:  stream
              path:  "%kernel.logs_dir%/%kernel.environment%.log"
              level: debug
          # send me an email when we have a critical error
          mail:
              type:         fingers_crossed
              action_level: critical
              handler:      buffered
          buffered:
              type:    buffer
              handler: swift
          swift:
              type:       swift_mailer
              from_email: %mailer_sender%
              to_email:   %error_email%
              subject:    "[FeedStream Error]"
              level:      debug
  </code></pre>
  
  <p>I saw: <a href="http://symfony.com/doc/current/cookbook/logging/monolog_email.html" rel="noreferrer">http://symfony.com/doc/current/cookbook/logging/monolog_email.html</a> But it doesn't handle <code>error</code> at all, which is a case where I still want logs (but no email).  I was pretty sure my config would work, but I don't know enough about the monolog settings.  Please let me know if this is correct or if there is a better way.</p>