Added User.

Added devise to manage the authentication.
Created User model.
Added logout link
Added support for editing profile
Added user information

Added nickname, first name and last name.
Added new controller to sanitize parameters.
Added registration controller test
Fix issue with test
Added security to BandsController
Added current_user as a band member when creating a band
Better display of band members
improve code. Fix typos
Improve tests
Merge pull request #3 from code-tailors/add_users

Add users