Plugin Gantt Versions Save

Make plugin compatible with Kanboard v1.2.4 and fix a couple of bugs.

• Remove access restriction for Manager only
• Add task sorting settings
• Only update start / due date if it has changed
• Use new date_due_not_defined and date_started_not_defined to show "gray" border instead of a completely black element
• Add task id and title in several places and prevent "text out of box" issue
• Remove deprecated PHP versions from Travis config
• Update Japanese translation

• Fix bug when using filter box

• Move Gantt charts outside of Kanboard