created items and configured back office ui a bit

app/models/Category.rb

@@ -1,4 +0,0 @@
-class Category < ActiveRecord::Base  
-  has_many :sub_categories
-  belongs_to :section
-end

app/models/category.rb

@@ -0,0 +1,4 @@
+class Category < ActiveRecord::Base
+  has_many  :sub_categories
+  belongs_to :section
+end

app/models/item.rb

@@ -0,0 +1,4 @@
+class Item < ActiveRecord::Base
+  belongs_to :unit
+  has_many :multi_media_descriptions
+end

app/models/media_type.rb

@@ -0,0 +1,3 @@
+class MediaType < ActiveRecord::Base
+  has_many :multi_media_descriptions
+end

app/models/multi_media_description.rb

@@ -0,0 +1,5 @@
+class MultiMediaDescription < ActiveRecord::Base
+  belongs_to :item
+  belongs_to :media_type
+
+end

app/models/section.rb

@@ -1,3 +1,3 @@
 class Section < ActiveRecord::Base
-    has_many :categories
+  has_many :categories
 end

app/models/unit.rb

@@ -0,0 +1,2 @@
+class Unit < ActiveRecord::Base
+end