Disable personal Herald rules from invalid owners

Summary: Since mailing list rules are now "global", don't run "personal" rules
for disabled/invalid users.

Test Plan: Added a personal rule that matches every revision for a test user.
Created a revision, checked transcript, rule matched. Disabled user, updated
revision, checked transcript, rule got auto-disabled.

Reviewers: btrahan, jungejason, nh, xela

Reviewed By: btrahan

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1517