Herald - make herald condition of herald rule display better

Summary: ...by the surprising step of changing how this data is stored from id to phid. Also a small fix to not allow "disabled" rules to be used as herald rule conditions, i.e. can't make a rule that depends on a disabled rule.

Test Plan: viewed existing herald rule that had a rule condition and noted nice new display using handle. made a new rule that had a rule condition and verified it worked correctly.

Reviewers: epriestley

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Differential Revision: https://secure.phabricator.com/D8186