feature: add cache/database instances to fields
feature: move assets/configurator instances to fields
feature: add default instance name constant
feature: change cache main key
feature: add get items method
bugfix: rename DEFAULT_INSTANCE_NAME constant
feature: change group_name for write items to DB
feature: set get_items to public *

* remove $_items field
* add DEFAULT_INSTANCE_NAME to skip configs
* get items by call get_items() in every action method
bugfix: sort items algo
feature: add get_config method *

* get configurator config in controller by get_config method
feature(view): add .input-sm class for input, select, textarea