Add Feature Dependency Injection

By passing $this to the closure that instantiates the class, it allows you to easily pass one container entry as a parameter to another container.

Add ArrayAccess Implentation

Implement ArrayAccess (#1)

* Add ArrayAccess methods

* Add ArrayAccess test file

* Add code for ArrayAccess methods

* Check if entry is callable

* Add tests for ArrayAccess interface

* Update example with ArrayAccess methods

* Update readme with ArrayAccess details

* Add ArrayAccess examples

* Add some more tests for ArrayAccess

* Add phpdoc for ArrayAccess methods

* Style tests

Initial Release

A very simple implementation of PSR-11. It has three methods: set, has, and get.