Brings intermission up to current production levels.

 * moves from /control to /_intermission/[enable|status|disable]
 * scopes pausing by app_name, if defined in nginx config
 * Allows monitoring paths through, if defined in nginx config
Adds capability to allow privileged user agent string to always pass, just like the health_check_path
Updated Contributors
Remove errant log message
Updated contributors
Typo
Fix critical bug where we would completely bail on requests with no user agent.
Merge pull request #2 from 37signals/updated-from-production

Brings intermission up to current with our (@37signals) production setup. Thanks @anoldguy for all your work on this!