Ignore locales without :general_lang_name key (#18110).

git-svn-id: http://svn.redmine.org/redmine/trunk@13450 e93f8b46-1217-0410-a6f0-8f06a7374b81
Use relative URL for thumbnails according to :only_path option (#18119).

git-svn-id: http://svn.redmine.org/redmine/trunk@13451 e93f8b46-1217-0410-a6f0-8f06a7374b81