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/post_replacements_controller.rb

@@ -24,13 +24,21 @@ class PostReplacementsController < ApplicationController
 
   def index
     params[:search][:post_id] = params.delete(:post_id) if params.key?(:post_id)
-    @post_replacements = PostReplacement.paginated_search(params)
+    @post_replacements = PostReplacement.paginated_search(params).includes(model_includes(params))
 
     respond_with(@post_replacements)
   end
 
   private
 
+  def default_includes(params)
+    if ["json", "xml"].include?(params[:format])
+      []
+    else
+      [:creator, {post: [:uploader]}]
+    end
+  end
+
   def create_params
     params.require(:post_replacement).permit(:replacement_url, :replacement_file, :final_source, :tags)
   end