Refactor javascript.

Eliminate all inline <script> tags and javascript function calls.
Rename admin-terms.js to admin-taxonomy.js
Utilize wp.media for collection posters.

Replace old-school upload field with WordPress 3.5's fancy modal
uploader.
Utilize wp.media for term images.

Replace the last of our old-school upload forms with wp.media modal
uploading.
Clean up.
More clean up.
Even more clean up.