Merged r13177 from trunk to 2.5-stable (#5706)

fix Ruby Logger doc link.

git-svn-id: http://svn.redmine.org/redmine/branches/2.5-stable@13178 e93f8b46-1217-0410-a6f0-8f06a7374b81
Merged r13180 from trunk to 2.5-stable (#17166)

Japanese translation updated by Go MAEDA.

git-svn-id: http://svn.redmine.org/redmine/branches/2.5-stable@13182 e93f8b46-1217-0410-a6f0-8f06a7374b81