Adds an outline for the different testing scenarios regarding the new operation input handling
Improves output of custom matchers
Extends matchers to support instantiating operation instances themselves and provide them with input if necessary

Meaning, matchers can now work with classes or instances.
Adds pry as a development dependency
Extracts common behavior of SucceedToPerform and FailToPerform matchers into a common super class
Improves the input processing and makes it more predictable
Fixes specs that have been breaking because of the new input processing
Adds specs to ensure that input propagation in processing pipelines works as expected
Updates README to reflect changes introduced by the new way of input parameter parsing
Version bump: v0.5.1 -> v0.6.0
Release v0.6.0