More work on Finder tagging

Click the preferences warning, click thru the warning and ALL FINDER
TAGS and ALL OM TAGS get merged and from then on, no way to go back,
nvALT will use Finder tagging.

For debugging purposes, check in AppController.h, set
k_FinderTaggingReset to 1   to have your preference for
useFinderTagging removed on launch. Quit, and set k_FinderTaggingReset
back to 0,  before doing anything.