Fix more JQMIGRATE notices from our jquery upgrade migration

[macnewbold]

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

[garinm90]

Hey, you have any requirements on contributing or can I just clone the repo and issue a PR?
If so, I'll look into updating any deprecated functions.