Add authentication spec for user

* Adds stubs for tasks pages

* Adds warden login_as helper for feature specs

* Adds spec testing login, logout and signup
Change devise token to use secrets.yml, add .ruby-version

* Remove secrets.yml from .gitignore, since it contains no
  keys that will be used in production

* Add .ruby-version while we're at it so CI runs the correct ruby

* Change config.secret_key in devise config to use the
  base_secret_key from Rails
Merge pull request #3 from paulnsorensen/add-authentication-spec

Add authentication spec for user