Allow save draft and publishing of the flowchart page within a modeladmin
Check if the getChartData returns null on empty data
Migrate flow chart pages chart data to the new API

CLI Usage:
./framework/sake dev/tasks/FlowChartMigrate flush=1

Via webserver:
/dev/tasks/FlowChartMigrate?flush=1
Merge pull request #3 from stojg/save-and-publish

Allow save draft and publishing of the flowchart page within a modeladmin