Issue #1684812 and #1261002 by quicksketch: Fix tabledrag and add touch support.

This is a replacement PR for https://github.com/backdrop/backdrop/pull/258.

Due to the difficulties comparing the change independently vs. Drupal 8's final JS, I incorporated both [JSHint tabledrag.js](http://drupal.org/node/1684812) and [Make Tabledrag.js touch-friendly](http://drupal.org/node/1261002).