Merge pull request #5 from valeragh/task3-beetlejuice_junction-table

Task3 beetlejuice junction table
refactor template controller
remove build method from item
update has_many through assosiation
update fill form
refactor categories controller
update item and category creating logic
refactor item and category controllers
rename item_category_values to values
refactor fill form and add scope :ordered to item and value