Fix tab size for Emacs users.

For some reason .dir-locals.el was setting tab-width to 2.  That's a Really
Bad Idea, because if somehow (as happened in my case) indent-tabs-mode was
't instead of nil like it should have been, Emacs will insert tabs instead
of spaces, and it'll *look* like it's doing the right thing.

Author: al45tair

.dir-locals.el

@@ -16,7 +16,6 @@
         (set (make-local-variable 'swift-project-directory)
          this-directory)
         )
-  (tab-width . 2)
   (fill-column . 80)
   (c-file-style . "swift"))
  (c++-mode