Updates for 2.3.1 release.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@11757 e93f8b46-1217-0410-a6f0-8f06a7374b81
Fixed: Unable to set custom fields for versions using the REST API (#13850).

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@11760 e93f8b46-1217-0410-a6f0-8f06a7374b81