add "assert_response 401" to tests (#16107)

git-svn-id: http://svn.redmine.org/redmine/trunk@12917 e93f8b46-1217-0410-a6f0-8f06a7374b81
explicitly set encoding UTF-8 (#16107)

Default Ruby source file encoding changed in Ruby 2.0.0.
https://bugs.ruby-lang.org/issues/6679

git-svn-id: http://svn.redmine.org/redmine/trunk@12918 e93f8b46-1217-0410-a6f0-8f06a7374b81