Changed learning design activities and transition collections to use all-delete-orphan cascade management. This will ensure that the secondary records are created and removed as required.This required fixing code that trigger cascade problems and also highlighted some session problems with the learner cache created by Jacky.
LDEV-61 Fixing tool sessions - all users were getting separate tool sessions.Modified learner service to suit changes to ToolActivity.createToolSessionForActivity()
modified it so that if it detects that the array of ToolPortfolios is null, it will just generate a main page stating that the portfolio export is not supported