move utf8 encoding from view to UnifiedDiff (#12641)

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@11545 e93f8b46-1217-0410-a6f0-8f06a7374b81
code cleanup (#12641)

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@11546 e93f8b46-1217-0410-a6f0-8f06a7374b81