Test skeleton non-gherkin steps default to 'Given'

[Dimwiddle]

Issue

Generating a skeleton where the scenario steps doesn't have gherkin syntax defaults specleft.steps() with 'Given'

Steps

/coding_projects/specleft 70-feature-c…nd-scenarios ⇡1 *3 ❯ spec features add-scenario --interactive
Feature ID: i-luv-specs
Scenario title: Misbehaving specs
Scenario ID: misbehaving-specs
Priority (critical, high, medium, low) [medium]: 
Tags: regression,hugs
Enter steps (blank line to finish):
Step: Add a scenario
Step: change mind about the scenario
Step: validate the scenario
Step: receive 422 error
Step: 
Generate test skeleton? [Y/n]: y
Test output directory [tests]: tests/acceptance/
Appended scenario:
  features/feature-i-luv-specs.md
  Feature ID: i-luv-specs
  Scenario ID: misbehaving-specs
  Title: Misbehaving specs
  Priority: medium
  Steps: 4

Warnings:
  - Step does not start with Given/When/Then/And/But: Add a scenario
  - Step does not start with Given/When/Then/And/But: change mind about the scenario
  - Step does not start with Given/When/Then/And/But: validate the scenario
  - Step does not start with Given/When/Then/And/But: receive 422 error