Fix corner-case when Scenarios are marked as skipped, but have no steps.
ADAPT: Undefined step schema snippet: impl() => step_impl()
ADAPT: Undefined step schema snippet for docs: impl() => step_impl()
AUTHORS: Add JE to authors.
Provide configfile for pychecker.
Merge branch 'master' of https://github.com/behave/behave
Update AUTHORS, tweak UNDEFINED-STEPS output schema, etc.
Apply fix for new UNDEFINED-STEP output schema.