add feature specs

[berlintam]

at the moment we only have model tests, but no feature specs. It would be great to have one & since the app is so small, it would be a nice introduction for those who haven't done one yet!

Feature spec should include visiting the root_page, clicking on "submit your own story", filling in the required fields, hitting submit, and then seeing your story on junior_stories_path (correctly formatted) . See https://github.com/rubycorns/rorganize.it/tree/master/spec/features for inspiration.

Also, this will require installing https://github.com/jnicklas/capybara first.