Added support to display flash[:error] and flash[:notice] in application.html.erb layout. Needs some css :)

Added routes to login, authenticate and logout; added a default root route to login.

Created PublicController, to hold all actions that do not require the user to be logged in.

Created PublicController#authenticate.

Created before_filter in ApplicationController, used in all private controllers.

Created logout method, linked it in the application layout.

Created User#full_name