Adding and removing tags in batch mode

Hello.
New feature in Batch tool (copy/update) allows to:
1. Remove all existing tags from selected items
2. Remove existing and add new tags
3. Keep existing and add new tags (if the tag has already been assigned, it will be skipped)



Please, check it and add to the master branch.

github.com/FLEXIcontent/flexicontent-cck...xicontent-cck:master

Thanks!

cool thanks