Move common nesting methods into shared file
Modify #fetch_path to allow usage on anything that responds to #fetch_path
Modify #store_path to allow usage on anything that responds to #store_path
Add nested methods to Array
Add tests for Array#fetch_path and Array#store_path
Move #has_key_path? for usage on anything that responds to #has_key_path?
Add tests for Array#has_key_path?