Fix more `JQMIGRATE` notices from our `jquery` upgrade migration

Currently 0.15.1 is throwing some JavaScript warnings from `jquery-migrate.js` that we should clean up. This probably isn't a complete list, but ones that I've run into so far include: - jQuery.trim is deprecated; use String.prototype.trim (from toolbar.js line 2 in `$.cookie`) - jQuery.fn.unbind() is deprecated (from toolbar.js line 146 in `hide_toolbar()` at `$(document).unbind('keydown.flDebug');`) There are also two that are issues within `jquery.tablesorter.js` so we may want to update to a newer version of that: - jQuery.isFunction() is deprecated (line 1029 in `buildCache`) - jQuery.fn.bind() is deprecated (line 484 in `bindEvents`) Environment: - Flask-DebugToolbar version: 0.15.1