Move Hook_Rest_Item --> Controller_Rest_Item.

--HG--
rename : modules/gallery/classes/Hook/Rest/Item.php => modules/gallery/classes/Controller/Rest/Item.php
rename : modules/gallery/classes/Gallery/Hook/Rest/Item.php => modules/gallery/classes/Gallery/Controller/Rest/Item.php
Fix class declarations for recently renamed files.
Trim Controller_Rest_Item::url() and resolve() functions.
Make Rest::get_resource() filter entity using "fields" parameter (if specified).
Set REST type and id in Controller_Rest::before() so they can be altered later.
This is useful, for example, for getting a random item.
Debug Controller_Rest and Rest a bit.
Make Controller_Rest::$default_params static.
Split up how Rest::entity() and members() function are called - make separate
functions for GET, PUT, POST, and DELETE.  Among other things, this makes it
easier to describe how PUT/POST relationships work.
Debug relationships in Rest::get_resource().
Add Controller_Rest::action_put(), action_post(), and action_delete() to handle
the typical actions for a REST resource.
Revise how Controller_Rest checks for undefined actions.
Fix method capitalization in Controller_Rest::before().
Complete rewrite of Controller_Rest_Item.
- fully implemented.
- mostly, but not entirely, tested (manually).
- Model_Item::as_restful_array() logic moved to Controller_Rest_Item.
Mark REST-related unit tests as incomplete.
Merge pull request #391 from shadlaws/fixes_20130610_2

Fixes 20130610 2