[FEATURE] Hexx::Dependencies module

The module provide methods for adding DI framework:

  # lib/my_gem.rb
  module MyGem
    extend Hexx::Dependencies
    self.depend_on :some_class
  end

  # config/by_gem.rb
  MyGem.configure do |config|
    config.some_class = "AnotherGem::SomeClass"
  end

  # somewhere in a code
  MyGem.some_class # => AnotherGem::SomeClass

== Addons

* Hexx::Dependencies