Support Spaces in Maniphest

Summary:
Ref T8493. Tricks:

  - "Create Similar Task" and "Create Subtask" should copy the parent's Space.
  - Normal list view + workboard card view.

Test Plan:
  - Created a task, edited space, etc.
  - Viewed tasks with different users.
  - Created a "Similar Task" (saw proper Space).
  - Created a subtask (saw proper Space).
  - Viewed workboard.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T8493

Differential Revision: https://secure.phabricator.com/D13232

resources/sql/autopatches/20150609.spaces.2.maniphest.sql

@@ -0,0 +1,2 @@
+ALTER TABLE {$NAMESPACE}_maniphest.maniphest_task
+  ADD spacePHID VARBINARY(64);