Subscriptions - make a dialog for massive subscription lists

Summary: Ref T4430. This just deploys it on the property lists. (Help on how to do translations better? I tried a more traditional pht('%s, %s, %s, and %d other(s)') but I think the string lookup assumes the %d comes as the second param or something?)

Test Plan: Made a Maniphest Task with a hojillion subscribers and noted the working dialogue. Also made a Pholio Mock with lots of subscribers and it worked.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: aran, epriestley, Korvin, chad

Maniphest Tasks: T4430

Differential Revision: https://secure.phabricator.com/D8525
Fix "arc diff --verbatim" when updating a revision

Summary: Fixes T4601. The "Differential Revision" field needs to be present in the "editable" version of the message so that `--verbatim` works correctly. Some day all of this might get rewritten to be a little easier to follow, maybe, but keep things working properly for now.

Test Plan: Used `arc diff`, `arc diff --edit`, `arc diff --verbatim`

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: aran, epriestley

Maniphest Tasks: T4601

Differential Revision: https://secure.phabricator.com/D8526
Fix "Send an email to" Herald rule for Differential

Summary: Herald returns a map of `phid => true`. This is unintuitive and should probably be cleaned up eventually.

Test Plan: With a "Send an email to" rule, updated a revision and saw no error in error log.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: aran, epriestley

Differential Revision: https://secure.phabricator.com/D8527
Add "Send an email" action to Herald for Maniphest

Summary: Fixes T4403. Supports the "send an email" action in Maniphest.

Test Plan: Wrote a "email duck" rule, then commented on a task and saw "duck" get an email.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: aran, epriestley

Maniphest Tasks: T4403

Differential Revision: https://secure.phabricator.com/D8529
In Differential mail, hide "summary" if empty and show "test plan" if nonempty

Summary:
Ref T4481. Summary is optional, but we currently always render it.

We previously rendered TEST PLAN. I wanted to see if anyone missed it. I miss it a little bit, and it sounds like @spicyj misses it. Restore it.

Test Plan:
  $ ./bin/mail show-outbound --id 15232
  ...
  BODY
  epriestley created this revision.
  epriestley added reviewers: The Bureaucracy, duck.
  epriestley added a subscriber: duck.

  TEST PLAN
    more j

  REVISION DETAIL
    http://local.aphront.com:8080/D1042

  AFFECTED FILES
    number_j.txt

  CHANGE DETAILS
    Index: number_j.txt
    ===================================================================
    --- number_j.txt
    +++ number_j.txt
    @@ -137,3 +137,4 @@
     j
     j
     j
    +j

  To: epriestley, duck, Sebastiangarcia, Ahmedsmoore, nathanhthomas, chewnicorn
  Cc: duck

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: aran, epriestley, spicyj

Maniphest Tasks: T4481

Differential Revision: https://secure.phabricator.com/D8531
Add a robots.txt file to disallow /diffusion/

Summary:
Fixes T4610. Open to suggestions, etc., if there's anything I'm missing.

Also:

  - Moves these "system" endpoints into a real application.
  - Makes `isUnlisted()` work a little more consistently.

Test Plan: Accessed `/robots.txt`, `/status/` and `/debug/`.

Reviewers: chad, btrahan

Reviewed By: btrahan

Subscribers: aran, epriestley

Maniphest Tasks: T4610

Differential Revision: https://secure.phabricator.com/D8532
Fix rendering of comments deleted by editing

Summary:
Fixes T4609. Steps are:

  - Make a comment.
  - Edit it.
  - Delete all the text.

We expect to see "This comment has been deleted." -- instead, things currently render goofy.

Root cause is that `hasComment()` means both "comment object exists" //and// "comment object is nonempty".

Test Plan: {F128862}

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: aran, epriestley

Maniphest Tasks: T4609

Differential Revision: https://secure.phabricator.com/D8533
Merge branch 'master' of http://github.com/facebook/phabricator