Support multiple targets for tabs

Created by: ukipme-jr

Bootstrap 3 supports multiple targets for tab controls - http://stackoverflow.com/questions/19719653/control-multiple-tab-contents-with-one-nav-tabs

Bootstrap 4 does not support this, yet, but it is a useful feature. I have added a basic workaround for time being:

file: /js/src/tab.js

line: 116 target = $(selector)[0] to target = $(selector)

line: 138 this._activate(target, target.parentNode, complete) to for (i=0; i<target.length; i++) { this._activate(target[i], target[i].parentNode, complete); }