Update cpt-bootstrap-carousel.php

Well, first of all, thanks for this plugin for WordPress.
I use it in mine projects, I note the little alteration in plugin make a big diference to me.

I think to, why not the options like interval, showcaption and showcontrols are in especifics news sliders backend options? I try make it and suggest a update but my knowlodge for can do that is poor for make it done.
In showcaption and controls, a checkbox for it [show = true, not show = false], and interval a input. Very like with URL option in new slide backend.

Thanks for your time... 

Hugs from Brazil.