Provide some diagnostic tools for examining inbound and outbound mail

Summary: We can't show this stuff on the web UI because it has password reset links and private reply-to addresses, but we can provide easier CLI tools than "root around in the database". Land a rough version of `bin/mail show-inbound` and `bin/mail show-outbound`.

Test Plan: Used both commands to examine mail from the CLI.

Reviewers: btrahan

Reviewed By: btrahan

CC: tido, euresti, aran

Differential Revision: https://secure.phabricator.com/D5963

scripts/mail/manage_mail.php

@@ -17,6 +17,8 @@ $args->parseStandardArguments();
 $workflows = array(
   new PhabricatorMailManagementResendWorkflow(),
   new PhutilHelpArgumentWorkflow(),
+  new PhabricatorMailManagementShowOutboundWorkflow(),
+  new PhabricatorMailManagementShowInboundWorkflow(),
 );
 
 $args->parseWorkflows($workflows);