Clean up Maniphest email "to"

Summary:
We currently try to send Maniphest email "To" the owner and actor, but for unassigned tasks there is no owner.

Just filter the PHIDs in the parent, since it's reasonable for subclasses to be liberal about construction here.

Test Plan: Commented on an unassigned task, got an email without a bogus "To".

Reviewers: btrahan, asherkin

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D7129
Make most repository reads policy-aware

Summary: Ref T603. This swaps almost all queries against the repository table over to be policy aware.

Test Plan:
  - Made an audit comment on a commit.
  - Ran `save_lint.php`.
  - Looked up a commit with `diffusion.getcommits`.
  - Looked up lint messages with `diffusion.getlintmessages`.
  - Clicked an external/submodule in Diffusion.
  - Viewed main lint and repository lint in Diffusion.
  - Completed and validated Owners paths in Owners.
  - Executed dry runs via Herald.
  - Queried for package owners with `owners.query`.
  - Viewed Owners package.
  - Edited Owners package.
  - Viewed Owners package list.
  - Executed `repository.query`.
  - Viewed "Repository" tool repository list.
  - Edited Arcanist project.
  - Hit "Delete" on repository (this just tells you to use the CLI).
  - Created a repository.
  - Edited a repository.
  - Ran `bin/repository list`.
  - Ran `bin/search index rGTESTff45d13dffcfb3ea85b03aac8cc36251cacdf01c`
  - Pushed and parsed a commit.
  - Skipped all the Drydock stuff, as it it's hard to test and isn't normally reachable.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T603

Differential Revision: https://secure.phabricator.com/D7132
Merge branch 'modifications'

Conflicts:
	webroot/rsrc/css/phui/phui-document.css