Use http://oauth-wrap-wg.googlegroups.com/web/SWT-v0.9.5.1.pdf to sign POST data going to SimianGrid with a shared secret set in the config file(s). This will be the primary security device in SimianGrid until we are generating per-region capabilities

Skipping this in favor of going straight to capability-based security. We might still need SWT for AD->RD communication, we'll see.