Remove the "Assign Terms" page

Issue Summary

I've decided after having some difficulty with my customized version of the Assign Terms page (#508710: Add the Ability to Exclude Vocabularies from the Taxonomy_Multi_Edit Screen), that it might be better for this module simply to remove that functionality entirely and focus on the "Assign to a taxonomy term" node operation which it adds to the admin/content/node page.

Now Views Tagger has been released (http://drupal.org/project/views_tagger), and it does a much better job of handling the assignment of terms to multiple nodes on a single page.