CoreFile: Now adds an incremental number

If the file already exists with the provided name
Merge pull request #19 from jmsche/patch-1

CoreFile: Now adds an incremental number
Merge pull request #21 from ANfactory/master

prevent Collection widget to add protoype item in possible children's collections
Added Twig dump() function service
Merge pull request #22 from jmsche/patch-2

Added Twig dump() function service
[js] corrected the way to count items in  FormCollection.addItem