Fix drag folder node in grid view/gen. stat.

Borrow the fix from following changeset
https://github.com/transmart/transmartApp/commit/951cced2188cf250451c824cf2b00c399eac08d5?diff=split
Fix drag folder node in grid view/gen. stat.

Caused by IllegalArgumentException: object is not an instance of declaring class
Merge branch 'master' of github.com:thehyve/transmartApp

Conflicts:
	grails-app/services/I2b2HelperService.groovy
Real fix: Fix drag folder node in grid view...

Caused by IllegalArgumentException: object is not an instance of declaring class
Merge pull request #1 from JnJtranSMART/master

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