BP mistral-actions-design (ad-hoc action)

* Created AdHocAction that works as a transforming wrapper
  for any other action (uses action specification dictionary)
* Added tests for AdHocAction
* Moved and refactored tests for email and echo actions from
  old package

TODO:
* Integrate AdHocAction with action factory (it is a special built-in
  action class and requires some special action on action factory side)
* Refactoring executor to use new action infrastructure
* Remove old action infrastructure
* Action plugin architecture

Partially implements: blueprint mistral-actions-design

Change-Id: Ieaf479047bfcaf3da61d40f28f108d198af6d16f