Devise bug fixes 04 08 2013 a

This pull request contains the following:

- Bug fixes related to User remember me functionality

- Modify the authenticated_system.rb file
  -  Refactor current_visitor method
  -  Remove methods
     - login_from_session
     - login_from_basic_auth
     - login_from_cookie
     - all the *_remember_cookie methods
  -  current_visitor= method is retained since it is used at a lot of places in the portal code