added bcrypt
added has_secure_password to user model
added create and destroy session methods in session controller
added current user helper method
changed users resource to users resources
added new user method, new session method with authentication, and destroy session method
changed question resources to questions resources
added user index, edit, update, and destroy
added tags controller
added before filters for edit routes
Merge pull request #6 from zacholauson/user_authentication

User authentication