add admin script to destroy a running app+data container pair
be less verbose during build to avoid truncating wercker log

Avoid message on app.wercker.com:

    The logs have been truncated (max log size: 1500000 bytes).
add table of contents to readme
update systemd service unit on upgrade

045122c2 updates the unit file on build;
we should also update the file on upgrade.
add stock password-auth pam config
optionally enable duosecurity for multi-factor auth

The default is to **not use** duo.
You must edit your local configuration in order to enable duo.
See the readme, global.conf, and login_duo.conf for details.