Stacked switches

Agreed. @yiyunma, this comment makes sense in the context of this pull request, but someone reading the code won't necessarily about know or be interested in this specific change - the idea that they're being "modified to support stacked switches" won't make a lot of sense - they're just being converted into the format the dell driver expects.

This is the sort of thing which, if it needs documentation, should be documented in the commit messages. In this case I think it can just be left out -- remove this line and I'll sign off on the pull request.