improvement for SD-491: text items creator

Added the list of creators to the text items. One can see now the original creator of the item and the list of all creators who ever made changes to the item. Also the number of the modified version is available with the corresponding creator.
From a previous discussion I understood that we need a list to keep all the authors for every version of an item. 
For the moment, in the implementation we have, we can see the original creator and the last creator who made the change for the latest version of an item.