change TaggerException policy in create/delete methods from Item

The TaggerException is ignored in those methods, to allow the construction
of the Item if there is a problem during the Tag processing.

In fact, if an exception is thrown during a multiple registration process,
it would cause more consistency damages than other things : the resulting Item
would be part tagged. The actual solution tag completely the Item, and there
may be some Tag registering the wrong Item -this consistency error is due to
the programmer-
update ItemTest methods with the new Item signatures

This update contain exception handle modification and new Tag consistency
checking (on construction, deletion and setName methods).

Tests relative to add/deleteTag has been removed (Item interface doesn't
provide anymore those methods)