[FEATURE] Accept a :cleanup controller in Dial
- The controller specified by the :cleanup parameter is run on each outbound call just before it is cleaned up
- :cleanup_metadata, if provided, is set on the :cleanup controller. If not provided, this defaults to :confirm_metadata
[CS] Remove the redundant .async when executing the :cleanup controller
[DOC] Add Changelog entry for the :cleanup controller dial option
Merge branch 'feature/dial-cleanup-controller' of https://github.com/CodeMangler/adhearsion into CodeMangler-feature/dial-cleanup-controller

Conflicts:
	CHANGELOG.md