Allow to return planned actions form sequence/concurrence blocks
Add #to_s representation to Steps::Error
Allow Steps::Error instants to rise exceptions easily

`raise error` will raise original exception
show the exception when planning fails
Add support for Action testing
TODOs update
Splitting #plan_action to #create_action and #plan_action

There is also #create_and_plan_action to run both
Add doc for Testing::Mimic
Rename assert_action_plan_planned to assert_action_plan

same goes for _with alternative
Support logger_adapter configuration in Testing
Better assertion names; adding type checks
Make Polling#external_task and Polling#done? public
Allow stubbing of run and finalize phases
Raise Error when trying to trigger on terminated executor
Add concurrent termination test
Checkin DB connections back to ActiveRecord pool when work is done
Reverse test_helper logger levels
Merge pull request #68 from pitr-ch/refactor

Add support for Action testing; other minor improvements pls see commit messages