create manage stage view
fix comments
ManageStageController updates view for add/deletes
ManageStageController updates model with add/deletes
ManageStageController can reorder stages now
Use stage IDs instead of names
update comments
Merge branch 'manage-stage-view' into dev-gradle
merge branch manage-stage-controller into dev-gradle
makes clicking toolbar buttons change the view, needs actual view objects instead of JPanels