add login page, show error message when login fails, write test for login failure
Added omniauth github for user login
Got rid of message in nav bar used for testing
1. use github authenticated user account to login, added two lines to omniauth.rb
2. move current_user function to session_helper.rb
3. add a dropdown menu for logged in user
1. combine Kevin's changes to login page.
registered a new github application for heroku
solve merging conflicts
Merge pull request #14 from DesignOpen/login

Use GitHub account to login