created sessions controller with new, create, destroy routes to log users in and out (pending testing of user authentication)
remove unnecessary comments
added link_to paths for signup/login to anonymous user menu
added gems for better errors and rails console:
compress validations for uniqueness to one line; added requirement for presence of password for has_secure_password
ability to logout added to standin anon menu partial
sessions controller with functional signing in and out
Merge pull request #11 from feministy/users_create_questions

User signup, login, and logout