Minor refactor rename feature file for consitency
Add regression scenarii

Minor allow multiple arguments methods to be modified by dummy app steps

The regression scenarii cover the default behaviour of the gem.
Add failing scenarii, add documentation
Add header_names option

Fixes #12
Update doc/features.html
Fix minor feature misspelling

The order of the sentences vary with RSpec random seed. I skipped
that the context was common to both spec examples.
Merge branch 'add-custom-header-names-option'
Bump version number