add failing test and uniq index to item_tags table
change item set_tags implementation and repair tests
исправлен тест "Не создает дубликатов имеющихся тегов"
optimisation set_tags method
Merge remote-tracking branch 'upstream/master' into feature-48-delete-tags-from-item

Conflicts:
	db/schema.rb
bad merged shema
Merge pull request #54 from monshq/feature-52-deleting-photos

Feature #52 deleting photos
Перенес тест в unit тесты, создал сценарий, создал хелпер для заполнения item
Merge pull request #50 from netDalek/feature-48-delete-tags-from-item

Feature 48 delete tags from item
fix missing tags after error while creating new item
add test for missing tags