Quote values in DOM selectors for Nokogiri compatibility.

git-svn-id: http://svn.redmine.org/redmine@13619 e93f8b46-1217-0410-a6f0-8f06a7374b81
Replaced some #assert_tag with #assert_select.

git-svn-id: http://svn.redmine.org/redmine@13620 e93f8b46-1217-0410-a6f0-8f06a7374b81
fix typo and use "GitHub" instead of "github" at CONTRIBUTING.md

git-svn-id: http://svn.redmine.org/redmine@13621 e93f8b46-1217-0410-a6f0-8f06a7374b81
German Self-registration translation changed by Filou Centrinov (#18392)

git-svn-id: http://svn.redmine.org/redmine@13622 e93f8b46-1217-0410-a6f0-8f06a7374b81
RTL css improvement (#18390)

git-svn-id: http://svn.redmine.org/redmine@13623 e93f8b46-1217-0410-a6f0-8f06a7374b81