Restore previously removed behaviors

[mvz]

Summary

Restore behaviors in master whose deprecation in 0.1.4.x was reverted.

Details

• Restore the API methods #in_current_directory, #all_stdout, #all_stderr, #all_output.
• Raise an error in output matchers when actual object does not respond to required methods. Previously, the matcher would just fail.
• Restore old behavior for output-matching cucumber steps, splitting them up a bit as well.

Motivation and Context

Fixes #641.

How Has This Been Tested?

Tests in 0.14.x for #in_current_directory were copied as well. The other methods are only tested through the cucumber scenarios at the moment.

Types of changes

• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Update documentation

Checklist:

• I've added tests for my code
• My change requires a change to the documentation.
• I have updated the documentation accordingly.