FEATURE: flag dispositions normalization

All flags should end up in one of the three dispositions
  - Agree
  - Disagree
  - Defer

In the administration area, the *active* flags section displays 4 buttons
  - Agree (hide post + send PM)
  - Disagree
  - Defer
  - Delete

Clicking "Delete" will open a modal that offer to
  - Delete Post & Defer Flags
  - Delete Post & Agree with Flags
  - Delete Spammer (if available)

When the flag has a list associated, the list will now display 1
response and 1 reply and a "show more..." link if there are more in the
conversation. Replying to the conversation will NOT give a disposition.
Moderators must click the buttons that does that.

If someone clicks one buttons, this will add a default moderator message
from that moderator saying what happened.

The *old* flags section now displays the proper dispositions and is
super duper fast (no more N+9999 queries).

FIX: the old list includes deleted topics
FIX: the lists now properly display the topic states (deleted, closed,
archived, hidden, PM)
FIX: flagging a topic that you've already flagged the first post

db/migrate/20140721162307_rename_defer_columns_on_post_action.rb

@@ -0,0 +1,17 @@
+class RenameDeferColumnsOnPostAction < ActiveRecord::Migration
+  def up
+    rename_column :post_actions, :defer_by, :defered_by_id
+
+    add_column :post_actions, :defered_at, :datetime
+    execute "UPDATE post_actions SET defered_at = updated_at WHERE defer = 't'"
+    remove_column :post_actions, :defer
+  end
+
+  def down
+    rename_column :post_actions, :defered_by_id, :defer_by
+
+    add_column :post_actions, :defer, :boolean
+    execute "UPDATE post_actions SET defer = 't' WHERE defered_at IS NOT NULL"
+    remove_column :post_actions, :defered_at
+  end
+end