Revert "prevent Redmine::Helpers::GanttTest error on Travis Ruby 1.9"

This reverts commit 08fbdb6f21b4aa1da884cde979e71b679bda576b.
Revert "prevent Redmine::Helpers::GanttTest error on Travis Ruby 1.9"

This reverts commit 74f596157daf3b57024d6ca21582ef89331a530b.
Test cleanup.

--HG--
extra : source : efa3d95a282c16487a567d2b8653dce344feab37