Merge pull request #1 from Mirantis/storage-skeleton-fix

Storage implementation skeleton fixed
Storage interface fixed

select_item, update_item methods were changed to meet DynamoDB
requirements
list_table api method fixed
Merge pull request #8 from dukhlov/master

Storage interface updated
Storage interface api not_indexed_condition_map renamed
Merge pull request #9 from dukhlov/master

Storage interface api not_indexed_condition_map renamed