Fix bug in property table

Fix bug in property table

When inserting a new entry in the property table and we're reusing
an entry from the free-list, make sure to assign the name correctly
to ensure we calculate the correct bucket according to the _new_
name and not the name from the old re-used property.

Also removed unused isEmpty() method that doesn't return the
correct thing anyway (_propertyCount is never decreased).

Change-Id: Ifc4f2f6b1c5fe975e30bdc81386061d6215ad3e3
Reviewed-by: Lars Knoll <lars.knoll@digia.com>