Add ability to use nested only parameter

- The only string works much the same as before with its comma separation
-- Nested includes are indicated with square brackets "[ ]"
-- The nested include is the value immediately preceding the square brackets
-- The only string is the comma separated string inside those brackets
- Default includes are split between format types when necessary
-- This prevents unnecessary includes from being added on page load
- Available includes are those items which are allowed to be accessible to the user
-- Some aren't because they are sensitive, such as the creator of a flag
-- Some aren't because the number of associated items is too large
- The amount of times the same model can be included to prevent recursions
-- One exception is the root model may include the same model once
--- e.g. the user model can include the inviter which is also the user model
-- Another exception is if the include is a has_many association
--- e.g. artist urls can include the artist, and then artist urls again

app/controllers/pools_controller.rb

@@ -17,7 +17,7 @@ class PoolsController < ApplicationController
   end
 
   def index
-    @pools = Pool.includes(:creator).paginated_search(params, count_pages: true)
+    @pools = Pool.paginated_search(params, count_pages: true).includes(model_includes(params))
 
     respond_with(@pools)
   end
@@ -90,6 +90,10 @@ class PoolsController < ApplicationController
 
   private
 
+  def default_includes(params)
+    [:creator]
+  end
+
   def item_matches_params(pool)
     if params[:search][:name_matches]
       Pool.normalize_name_for_search(pool.name) == Pool.normalize_name_for_search(params[:search][:name_matches])