Ensure logging in ~/.msf4/log

 Fix rapid7#4511

Author: trevrosen

config/application.rb

@@ -34,6 +34,7 @@ module Framework
     class Application < Rails::Application
       include Metasploit::Framework::CommonEngine
 
+      config.paths['log']             = "#{Msf::Config.log_directory}/#{Rails.env}.log"
       config.paths['config/database'] = [Metasploit::Framework::Database.configurations_pathname.try(:to_path)]
     end
   end