Consider indicating Need Info issues in issue summary

[bgilbert]

Sometimes an issue is marked Need Info and we're waiting on the reporter, but we don't want to time out the issue because we know that it's valid. It'd be nice to indicate this state in the issue message by changing the icon and status line, so we don't click through only to discover that there's nothing to be done.

During regular polling, we'd need to walk every unresolved issue that doesn't have a timeout enabled, and refresh the issue message if its Need Info status changed. Presumably we don't want to refresh every unresolved issue every 5 minutes, so we'd need a database column recording whether Need Info was previously set.

Suggested by @jlebon.