Clean up some EditEngine meta-policies

Summary:
Ref T9908. Simplify some of the policies here:

  - If you can edit an application (currently, always "Administrators"), you can view and edit all of its forms.
  - You must be able to edit an application to create new forms.
  - Improve some error messages.
  - Get about halfway through letting users reorder forms in the "Create" menu if they want to sort by something weird since it'll need schema changes and I can do them all in one go here.

Test Plan:
  - Tried to create and edit forms as an unprivileged user.
  - Created and edited forms as an administrator.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T9908

Differential Revision: https://secure.phabricator.com/D14700

resources/sql/autopatches/20151207.editengine.1.sql

@@ -0,0 +1,11 @@
+ALTER TABLE {$NAMESPACE}_search.search_editengineconfiguration
+  DROP editPolicy;
+
+ALTER TABLE {$NAMESPACE}_search.search_editengineconfiguration
+  ADD isEdit BOOL NOT NULL;
+
+ALTER TABLE {$NAMESPACE}_search.search_editengineconfiguration
+  ADD createOrder INT UNSIGNED NOT NULL;
+
+ALTER TABLE {$NAMESPACE}_search.search_editengineconfiguration
+  ADD editOrder INT UNSIGNED NOT NULL;